Porcelain
5
162
4
to
62
123
42
166
166
166
41
18
8
5
5
1
1
162
4
23
57
69
1
4
13
2
12
8
12
17
34
6
165
162
3
3
2
162
153
3
3
1
3
373
165
165
157
Porcelain For Sale
Creator: Rosenthal
Creator: Dahl Jensen
Bjørn Wiinblad Christmas Plate 1972 "Caspar"
Located in Brønshøj, DK
Bjørn Wiinblad porcelain Christmas plate 1972, produced by Rosenthal.
Motif: The Holy Three Kings
Designed by: Bjørn Wiinblad
Diameter: 11" - 29 cm
Comes in original box. The ...
Category
1970s German Vintage Porcelain
Materials
Porcelain
Bjørn Wiinblad Christmas Plate 1990 "Christmas Carols"
Located in Brønshøj, DK
Bjørn Wiinblad porcelain Christmas plate 1990, produced by Rosenthal
Motif: Leise rieselt der Schnee
Designed by: Bjørn Wiinblad
Diameter: 11" - 29 cm
Comes in original box and ...
Category
1990s German Porcelain
Materials
Porcelain
Bjørn Wiinblad Christmas plate 1983 "Nativity of Jesus"
Located in Brønshøj, DK
Bjørn Wiinblad porcelain Christmas plate 1983, produced by Rosenthal
Motif: Silent Night Holy Night
Designed by: Bjørn Wiinblad
Diameter: 11" - 29 cm
Comes in original box and p...
Category
1980s German Vintage Porcelain
Materials
Porcelain
Porcelain Casket Jewellery Box, Rosenthal Chippendale, Germany, 1942
By Rosenthal
Located in Chorzów, PL
Porcelain casket - a box for jewelry and trinkets.
Ivory-colored porcelain decorated with gilding and a floral bouquet motif.
A product of the re...
Category
1940s German Chippendale Vintage Porcelain
Materials
Porcelain
Large Porcelain Figurine 'Cabaret', by R. Marcuse, Rosenthal Selb Germany, 1920
By Rosenthal
Located in Vienna, AT
Art Nouveau beauty with chin-length dark brown hair, in a strapless dress with a deep neckline decorated with elaborate floral embroidery at the front and back and a softly falling, wave-like billowing skirt hem, posing bent to the side and playing a lute.
Based on a round, white, fluted plinth, artist's signature 'RUDOLF MARCUSE...
Category
1920s German Art Nouveau Vintage Porcelain
Materials
Porcelain
Bjørn Wiinblad Christmas plate 1971 "Mary with baby Jesus"
Located in Brønshøj, DK
Bjørn Wiinblad porcelain Christmas plate 1971, produced By Rosenthal.
Motif: Maria with the Child
Designed by: Bjørn Wiinblad.
Diameter: 11" - 29 cm
Comes in original box. Box h...
Category
1970s German Vintage Porcelain
Materials
Porcelain
Vintage Plate Christmas Carols on Porcelain "Silent night, holy night" Rosenthal
Located in Bastogne, BE
Vintage wall plate Christmas Carols on Porcelain: "Silent night, holy night" by ROSENTHAL Germany studio-line. 1983.
Limited edtion designed by B...
Category
1980s German Vintage Porcelain
Materials
Porcelain
Bjørn Wiinblad Christmas Plate 1980 "Angel with Bells"
Located in Brønshøj, DK
Bjørn Wiinblad porcelain Christmas plate 1980, produced by Rosenthal
Motif: The Angel and the Glockenspiel
Designed by: Bjørn Wiinblad
Diameter: 11" - 29 cm
Comes in original bo...
Category
1980s German Vintage Porcelain
Materials
Porcelain
Bjørn Wiinblad Christmas plate 1988 "Christmas Carols"
Located in Brønshøj, DK
Bjørn Wiinblad porcelain Christmas plate 1988, produced by Rosenthal
Motif: Süsser die Glocken nie klingen
Designed by: Bjørn Wiinblad
Diameter: 11" - 29 cm
Comes in original bo...
Category
1980s German Vintage Porcelain
Materials
Porcelain
Bjørn Wiinblad Christmas Plate 1974 "Balthasar"
Located in Brønshøj, DK
Bjørn Wiinblad porcelain Christmas plate 1974, produced by Rosenthal
Motif: The Holy Three Kings
Designed by: Bjoern Wiinblad
Diameter: 11" - 29 cm
Comes in original box. Box h...
Category
1970s German Vintage Porcelain
Materials
Porcelain
Raymond Loewy for Rosenthal ‘Form 2000' Coffee Pot, Designed 1954, White Ceramic
Located in London, GB
Raymond Loewy and Richard Latham for Rosenthal, 1954
‘Form 2000’ Coffee Pot
A lovely example of this design classic
White ceramic with gold edging
Exce...
Category
1950s German Mid-Century Modern Vintage Porcelain
Materials
Ceramic
Bjorn Wiinblad Christmas Plate 1973 "Melchior"
Located in Brønshøj, DK
Bjørn Wiinblad porcelain Christmas plate 1973, produced by Rosenthal
Motif: Melchior
Designed by: Bjørn Wiinblad
Diameter: 11" - 29 cm
Comes in original box. Box has signs of we...
Category
1970s German Vintage Porcelain
Materials
Porcelain
Large Porcelain Group 'Joy of Life' by J. Limburg Rosenthal Selb Germany Ca 1923
Located in Vienna, AT
Extremely Rare Large Art Nouveau Group:
Monumental figure of Flora with chin-length hair in a long dress loosely embracing the beautiful body, her right foot resting on a low pedest...
Category
1920s German Art Nouveau Vintage Porcelain
Materials
Porcelain
Post-Modern Espresso Set by Frauke V. Jaruntowski for Rosenthal Studio-Line
By Rosenthal
Located in San Diego, CA
Post-Modern espresso cup and saucer set by Frauke V. Jaruntowski for Rosenthal Studio-Line, circa 1980s. This wonderful set is in great vintage condition with no chips or cracks, is...
Category
Late 20th Century German Post-Modern Porcelain
Materials
Porcelain
Porcelain Coffee Service, Rosenthal Sanssouci, 1946, 42 Pieces
By Rosenthal
Located in Chorzów, PL
Rosenthal porcelain service, model Sanssouci, 1946, 42 pieces.
Very good condition.
the set includes:
- jug height 26 cm width 17 cm depth 11 cm
- sugar bowl, height 13 cm, width...
Category
1940s German Vintage Porcelain
Materials
Porcelain
Rosenthal Germany Versace Porcelain Black, Red, White, Gold Medusa 2 Part Box
By Rosenthal
Located in North Miami, FL
This lovely Rosenthal Studio LIne Germany porcelain 2 part round box was designed by the Versace Home Collection and has the fabulous Medusa head and from the Medusa collection. It i...
Category
2010s German Regency Revival Porcelain
Materials
Porcelain
Bjørn Wiinblad Christmas Plate 1982 "Baptism of Jesus"
Located in Brønshøj, DK
Bjørn Wiinblad porcelain Christmas plate 1982, produced by Rosenthal
Motif: John the Babtist
Designed by: Bjørn Wiinblad
Diameter: 11" - 29 cm
Comes in original box. Box has sig...
Category
1980s German Vintage Porcelain
Materials
Porcelain
Openwork Plate, Rosenthal Moliere, Germany, 1938-1952
By Rosenthal
Located in Chorzów, PL
A plate with openwork sides from the Moliere series by the renowned German Rosenthal porcelain factory.
Ecru porcelain decorated with gilding on the edges and a floral bouquet mot...
Category
Mid-20th Century German Porcelain
Materials
Porcelain
Two Saucers, Rosenthal Chippendale, Germany, 1945-1946
By Rosenthal
Located in Chorzów, PL
Two small plates for putting away e.g. tea or serving side dishes on the table.
Plates from the Chippendale series from the excellent German Rosenthal label.
Very good condition.
...
Category
1940s German Chippendale Vintage Porcelain
Materials
Porcelain
Platter on legs, Rosenthal Moliere Moosrose, 1938-1952
By Rosenthal
Located in Chorzów, PL
Openwork plate supported on three filigree legs from the Moliere collection, the renowned German Rosenthal label. The product is marked with the mark used in the years 1938-1952. Por...
Category
Mid-20th Century German Porcelain
Materials
Porcelain
Plate on legs, Rosenthal Moliere, 1957
By Rosenthal
Located in Chorzów, PL
Openwork plate supported on three filigree legs from the Moliere collection, the renowned German Rosenthal label. The product is marked with the mark used in 1957. Ecru porcelain dec...
Category
Mid-20th Century German Porcelain
Materials
Porcelain
Openwork Plate, Rosenthal Moliere, Germany, 1957
By Rosenthal
Located in Chorzów, PL
A plate with openwork sides from the Moliere series by the renowned German Rosenthal porcelain factory. Ecru porcelain decorated with gilding on the edges and a floral bouquet motif....
Category
1940s German Vintage Porcelain
Materials
Porcelain
Bjørn Wiinblad Christmas plate 1981 "Boy Jesus at the Temple"
Located in Brønshøj, DK
Bjørn Wiinblad porcelain Christmas plate 1981, produced by Rosenthal
Motif: The Child with the scholars in the Temple
Designed by: Bjørn Wiinblad
Diameter: 11" - 29 cm
Comes in ...
Category
1980s German Vintage Porcelain
Materials
Porcelain
Porcelain Coffee Service, Rosenthal White Maria, 1927
By Rosenthal
Located in Chorzów, PL
Porcelain coffee service for 12 people. White porcelain with flowers from the excellent German manufacturer Rosenthal. Signed with a mark from 1927.
the set includes:
- pitcher
- ...
Category
1920s German Vintage Porcelain
Materials
Porcelain
Saucer, Rosenthal, Germany, 1953
By Rosenthal
Located in Chorzów, PL
A small "depositor" plate used to put away e.g. tea or to serve side dishes on the table.
A plate from the excellent German Rosenthal label. Signed with...
Category
1950s German Chippendale Vintage Porcelain
Materials
Porcelain
Openwork Plate, Rosenthal Moliere, Germany, 1938-1952
By Rosenthal
Located in Chorzów, PL
A plate with openwork sides from the Moliere series by the renowned German Rosenthal porcelain factory.
Ecru porcelain decorated with gilding on the edges and a floral bouquet mot...
Category
Mid-20th Century German Porcelain
Materials
Porcelain
Die Zauberflötte the Magic Flute Bjørn Wiinblad for Rosenthal Espresso Set
Located in Miami, FL
Reduced From $2,500...Rosenthal Studio Linie by Bjørn Wiinblad Die Zauberflöte Expresso Coffee Set. With the design for the Rosenthal Studio Linie The Magic Flute, the Danish artist...
Category
1970s German Mid-Century Modern Vintage Porcelain
Materials
Porcelain
Porcelain Box, Rosenthal Chippendale, Germany, 1949
By Rosenthal
Located in Chorzów, PL
Porcelain casket with a lid - a box from the Chippendale collection, made in Germany by the excellent Rosenthal factory. Ivory-colored porcelain decorated with gilding on the edges a...
Category
1940s German Chippendale Vintage Porcelain
Materials
Porcelain
Saucer, Rosenthal, Germany, 1953
By Rosenthal
Located in Chorzów, PL
A small "depositor" plate used to put away e.g. tea or to serve side dishes on the table.
A plate from the excellent German Rosenthal label. Signed with...
Category
1950s German Chippendale Vintage Porcelain
Materials
Porcelain
Tapio Wirkaala "Porcelaine Noire" Dish Plate for Rosenthal Studio Linie, 1970s
Located in Reggio Emilia, IT
Vintage dish plate in black porcelain designed by Tapio Wirkkala for Rosenthal Studio Linie “Porcelaine Noire” serie with shiny and matte tone-on-tone dec...
Category
1970s German Post-Modern Vintage Porcelain
Materials
Porcelain
Bowl with Gilding, Rosenthal Chippendale, Germany, 1940s
By Rosenthal
Located in Chorzów, PL
Beautiful porcelain platter-bowl in ecru color decorated with gilding and a floral motif
A product of the valued German Rosenthal label, marked with a mark used in the 1940s.
A...
Category
1940s German Chippendale Vintage Porcelain
Materials
Porcelain
Rosenthal Porcelain Coffee Set, Germany, 1923-1925
By Rosenthal
Located in Chorzów, PL
A pre-war Rosenthal porcelain set from 1923-1925.
Very good condition.
the set includes:
- jug height 13 cm width 25 cm depth 15 cm
- sugar...
Category
1920s German Vintage Porcelain
Materials
Porcelain
Openwork Plate, Rosenthal Moliere, Germany, 1938-1952
By Rosenthal
Located in Chorzów, PL
A plate with openwork sides from the Moliere series by the renowned German Rosenthal porcelain factory.
Ecru porcelain decorated with gilding on the edges and a floral bouquet mot...
Category
Mid-20th Century German Porcelain
Materials
Porcelain
Porcelain Box, Rosenthal, Germany, 1910
By Rosenthal
Located in Chorzów, PL
Porcelain casket made of white porcelain, decorated with a floral motif.
The gilding is slightly worn, very good condition, no cracks or chips.
Casket signed with a mark from 1910....
Category
1910s German Vintage Porcelain
Materials
Porcelain
Bjørn Wiinblad Christmas Plate 1975 "Annunciation to the Blessed Virgin Mary"
Located in Brønshøj, DK
Bjørn Wiinblad porcelain Christmas plate 1975, produced by Rosenthal
Motif: The Proclamation
Designed by: Bjørn Wiinblad
Diameter: 11" - 29 cm
Comes in original box. Box has sig...
Category
1970s German Vintage Porcelain
Materials
Porcelain
Bjørn Wiinblad Christmas Plate 1985 "The Three Magi Follow the Star"
Located in Brønshøj, DK
Bjørn Wiinblad porcelain Christmas plate 1985, produced by Rosenthal
Motif: We three kings of Orient are
Designed by: Bjørn Wiinblad
Diameter: 11" - 29 cm
Comes in original box ...
Category
1980s German Vintage Porcelain
Materials
Porcelain
Openwork Plate, Rosenthal Moliere, Germany, 1945-1946
By Rosenthal
Located in Chorzów, PL
A plate with openwork sides from the Moliere series by the renowned German Rosenthal porcelain factory.
Ecru porcelain decorated with gilding on the edges and a rose motif.
Signed ...
Category
1940s German Vintage Porcelain
Materials
Porcelain
1990s, Iconic Porcelain Medusa Vase Designed by Gianni Versace for Rosenthal
Located in Aci Castello, IT
A red and gold porcelain vase designed by Gianni Versace and manufactured by Rosenthal in the Nineties. It's in perfect conditions, probably never used. The Medusa it's always used by Gianni Versace and also now it's often present in Versace collections. The Medusa was one of the 3 Gorgons...
Category
Late 20th Century German Neoclassical Revival Porcelain
Materials
Porcelain
Bjørn Wiinblad Christmas Plate 1977 "Shepherds Greet the Newborn King"
Located in Brønshøj, DK
Bjørn Wiinblad porcelain Christmas plate 1977, produced by Rosenthal
Motif: The Herds' arrival
Designed by: Bjørn Wiinblad
Diameter: 11" - 29 cm
Comes in original box. Box has s...
Category
1970s German Vintage Porcelain
Materials
Porcelain
Porcelain Box, Rosenthal Chippendale, Germany, 1949
By Rosenthal
Located in Chorzów, PL
Porcelain casket with a lid - a box from the Chippendale collection, made in Germany by the excellent Rosenthal factory. Ivory-colored porcelain decorated with gilding on the edges a...
Category
1940s German Chippendale Vintage Porcelain
Materials
Porcelain
Openwork Plate, Rosenthal Moliere, Germany, 1938-1952
By Rosenthal
Located in Chorzów, PL
Porcelain openwork platter made of ecru porcelain, decorated with gilding and a bouquet of flowers motif. A product of the valued German manufacture...
Category
1940s German Vintage Porcelain
Materials
Porcelain
Porcelain Platter, Rosenthal Moliere, Germany, 1938-1952
By Rosenthal
Located in Chorzów, PL
Porcelain openwork platter made of ecru porcelain, decorated with gilding and a bouquet of flowers motif. A product of the valued German manufacture...
Category
1950s German Vintage Porcelain
Materials
Porcelain
Bjørn Wiinblad Christmas Plate 1976 "Angel of the Trumpet"
Located in Brønshøj, DK
Bjørn Wiinblad porcelain Christmas plate 1976, produced by Rosenthal
Motif: The Angel and her Trompet
Designed by: Bjørn Wiinblad
Diameter: 11" - 29 cm
Comes in original box. Bo...
Category
1970s German Vintage Porcelain
Materials
Porcelain
Platter on Legs, Rosenthal Moliere, 1945
By Rosenthal
Located in Chorzów, PL
Openwork plate supported on three filigree legs from the Moliere collection, the renowned German Rosenthal label. The product is marked with the mark used in 1945. Ecru porcelain dec...
Category
Mid-20th Century German Porcelain
Materials
Porcelain
Openwork plate, Rosenthal Moliere, Germany, 1938-1952
By Rosenthal
Located in Chorzów, PL
A plate with openwork sides from the Moliere series by the renowned German Rosenthal porcelain factory.
Ecru porcelain decorated with gilding on the edges and a floral bouquet mot...
Category
Mid-20th Century German Porcelain
Materials
Porcelain
Bjørn Wiinblad Christmas plate 1979 "The flight to Egypt"
Located in Brønshøj, DK
Bjørn Wiinblad porcelain Christmas plate 1979, produced by Rosenthal
Motif: The Flight to Egypt
Designed by: Bjørn Wiinblad
Diameter: 11" - 29 ...
Category
1970s German Vintage Porcelain
Materials
Porcelain
Rosenthal Kronach Viktoria German Porcelain Floral Design Coffee Set, 27 Pieces
By Rosenthal
Located in Plainview, NY
1930's Rosenthal Kronach Viktoria Lombul gold trim German porcelain large coffee set of 27 pieces decorated in a floral prink rose motif on white. Ea...
Category
20th Century German Victorian Porcelain
Materials
Porcelain
Saucer, Rosenthal, Germany, 1920
By Rosenthal
Located in Chorzów, PL
A small "depositor" plate used to put away e.g. tea or to serve side dishes on the table.
A plate from the excellent German Rosenthal label. Signed with...
Category
1920s German Chippendale Vintage Porcelain
Materials
Porcelain
Pot-Pourri Container, Rosenthal, 1930
By Rosenthal
Located in Chorzów, PL
Container for fragrant dried flower petals pot pourri.
A product of the valued German Rosenthal label, marked with a mark from 1930.
The lid of the container is slightly chipped on...
Category
1930s German Vintage Porcelain
Materials
Porcelain
Porcelain Bowl with Gilding, Rosenthal, Germany, 1949
By Rosenthal
Located in Chorzów, PL
Porcelain bowl without a lid, produced by the excellent German Rosenthal factory in 1949. Very good condition, no damage.
Height 5 cm, Diameter 12.5 cm.
Category
1940s German Vintage Porcelain
Materials
Porcelain
Björn Wiinblad for Rosendhal Studio Linie White Porcelain Bowl, 1970s
Located in Reggio Emilia, IT
Original Rosenthal Germany Studio Linie white porcelain bowl,
designed by Danish artist Björn Wiinblad, circa 1970.
Signature of manufacturer and designer under the base.
Category
1970s German Mid-Century Modern Vintage Porcelain
Materials
Porcelain
Postmodern Grey Earthenware Vase by Rosenthal, Italy
By Rosenthal
Located in Bresso, Lombardy
Made in Italy, 1980s
This ceramic vase is marked by Rosenthal.
This is a vintage piece, therefore it might show slight traces of use, but it can be considered as in excellent origin...
Category
1980s European Post-Modern Vintage Porcelain
Materials
Earthenware
Porcelain Figurine "Child with a Dog", Rosenthal, Germany, 1940s
By Rosenthal
Located in Chorzów, PL
Porcelain figurine of a child with a dog produced by Rosenthal in Germany in the 1940s.
Perfect condition, no damage
Measures: height 16cm, width 14cm, depth 7cm.
Category
1940s German Art Deco Vintage Porcelain
Materials
Porcelain
Large Art Deco Figure Group 'Young Love' by J. Limburg Rosenthal, Germany
By Rosenthal
Located in Vienna, AT
Admirable Rosenthal figurine group by Josef Limburg
Manufactory: Rosenthal / Selb / Bavaria / Germany
Dating: manufactured circa 1925
Material and technique: porcelain / chinaware / painted / glossy finish
Design: Josef Limburg 1923
'Young Love'
Two naked cherubs kissing each other; a seated putto hugs the second boy
crawling towards him and kisses him on the mouth; modest painting;
The group of figures is based on a flat rock...
Category
1920s German Art Deco Vintage Porcelain
Materials
Porcelain
Mid-Century Romanze Porcelain Dinner Service by Bjorn Wiinblad for Rosenthal
Located in Philadelphia, PA
A fine, near complete Mid-Century modern porcelain dinner service.
By Bjorn Wiinblad for Rosenthal.
In the Romanze form and Medley pattern.
Consisting of:
10 Large Dinner Plates
...
Category
Mid-20th Century German Mid-Century Modern Porcelain
Materials
Porcelain
Three Piece Post-Modern "Love Cups" Set by Katja Marzahn for Rosenthal
By Rosenthal
Located in San Diego, CA
Three piece post-modern "Love Cups" set by Katja Marzahn for Rosenthal Studio-Line, circa 1980s. This wonderful cupola espresso set is made of porcelain with...
Category
Late 20th Century German Post-Modern Porcelain
Materials
Porcelain
Mid-Century Rosenthal by Raymond Loewy Form 2000 Partial Dinner Set: 26 Pcs
By Rosenthal
Located in Hamilton, Ontario
This partial dinner ware set was made by the well known Rosenthal factory of Germany in approximately 1970 in the period Mid-Century Modern style. The ...
Category
Mid-20th Century German Mid-Century Modern Porcelain
Materials
Porcelain
Post-Modern "Kunstlertasse #9" Set by Beate Kuhn for Rosenthal Studio Line
By Rosenthal, Beate Kuhn
Located in San Diego, CA
Post-Modern "Kunstlertasse #9" cup and saucer set by Beate Kuhn for Rosenthal Studio-Line, circa 1980s. This wonderful set is in great vintage condition with no chips or cracks, is m...
Category
Late 20th Century German Post-Modern Porcelain
Materials
Porcelain
Antique and Vintage Porcelain Dinner Plates, Platters and Serveware for Sale
Today you’re likely to bring out your antique and vintage porcelain in order to dress up your dining table for a special meal.
Porcelain, a durable and nonporous kind of pottery made from clay and stone, was first made in China and spread across the world owing to the trade routes to the Far East established by Dutch and Portuguese merchants. Given its origin, English speakers called porcelain “fine china,” an expression you still might hear today. "Fine" indeed — for over a thousand years, it has been a highly sought-after material.
Meissen Porcelain, one of the first factories to create real porcelain outside Asia, popularized figurine centerpieces during the 18th century in Germany, while works by Capodimonte, a porcelain factory in Italy, are synonymous with flowers and notoriously hard to come by. Modern porcelain houses such as Maison Fragile of Limoges, France — long a hub of private porcelain manufacturing — keep the city’s long tradition alive while collaborating with venturesome contemporary artists such as illustrator Jean-Michel Tixier.
Porcelain is not totally clumsy-guest-proof, but it is surprisingly durable and easy to clean. Its low permeability and hardness have rendered porcelain wares a staple in kitchens and dining rooms as well as a common material for bathroom sinks and dental veneers. While it is tempting to store your porcelain behind closed glass cabinet doors and reserve it only for display, your porcelain dinner plates and serving platters can safely weather the “dangers” of the dining room and be used during meals.
Add different textures and colors to your table with dinner plates and pitchers of ceramic and silver or a porcelain lidded tureen, a serving dish with side handles that is often used for soups. Although porcelain and ceramic are both made in a kiln, porcelain is made with more refined clay and is stronger than ceramic because it is denser.
On 1stDibs, browse an expansive collection of antique and vintage porcelain made in a variety of styles, including Regency, Scandinavian modern and other examples produced during the mid-century era, plus Rococo, which found its inspiration in nature and saw potters crafting animal figurines and integrating organic motifs such as floral patterns in their work.
Recently Viewed
View AllMore Ways To Browse
White China Dishes
Oval German Plate
18th Century Japanese Plate
Porcelain Warming Plate
Antique Chelsea Porcelain
Gilded Export Porcelain
Antique Japanese Imari Porcelain Plate Plates
Hand Paint China Dishes
Chinese Porcelain Teapot
Covered Meissen
Rimmed Soup Plates
Dresden Meissen Figurines
Vintage Silver Dishes
Early Derby Porcelain
Qing Dynasty Silver
Letter Porcelain
Meissen Porcelain Covered
Hand Painted Botanical Porcelain