Ruri Glaze (Ruriyu): Deep Cobalt Blue on Japanese Pottery

Ruri glaze (ruriyu) is a glaze colored by cobalt that covers the surface of a piece in deep blue. The name compares it to the deep blue of ruri, the gemstone lapis lazuli.

The blue comes from cobalt, the same as the gosu used to paint sometsuke. The difference is how it is used. Sometsuke paints a picture on the body in gosu and covers it with a clear glaze, while ruri glaze dissolves the cobalt into the glaze itself and dyes the whole piece blue. Where the glaze is thick it is darker, and rims and raised areas turn a little lighter, so even a single color has light and shade.

Ruri Glaze and Other Blue Pottery

Blue That Mirrors the Water at Dawn: mizuki (Lazuli) Pottery

mizuki makes pottery at a studio at the foot of the mountains in Seto, Aichi Prefecture, around the theme of "capturing a moment of nature," under the brand name "Lazuli." The studio makes the original form of the waves from the clay itself and transfers its texture onto the surface of each piece, so the wave pattern appears in relief.

The photo at the top is a plate from "Yoake" (dawn), Lazuli's signature series. The shading of the glaze, shifting from deep ruri to pale blue, mirrors the moment light begins to fall on dark water. The gradation of blue, made by spraying layer upon layer of glaze, meets the texture of the waves: deep blue pools in the grooves, and the crests catch the light and look brighter.

From left, the photo shows half-moon flat plates in "Yoake," "Socho" and "Gengetsu." The "Socho" (clear morning) series shifts from a translucent turquoise to deep ruri, like clear water sparkling in the morning light. The same series also includes a round flat plate about 21.5 cm across, just the right size for appetizers, cheese or an assortment of cakes. Every piece comes in a gift box, so they also make good gifts.

The Same Shapes in Ruri: Furutani Pottery's Ruri Glaze

Furutani pottery in Shigaraki is a studio known for soft kohiki white and lines of iron, but it also makes a series of octagonal plates, octagonal cake plates, lobed bowls and apple bowls finished in ruri glaze. The octagonal plate also comes in gray glaze and rust glaze in the same shape, and even with the shape unchanged, switching the glaze completely changes the look of the piece. Set beside white kohiki pieces, the blue of ruri looks even deeper. The studio's story is in our profile of Furutani pottery.

Ruri Blue for Everyday Tools, Too: Kanefusa Seito's Donabe

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Ruri glaze is used not only on pieces for display but also on tools for everyday use. The photo shows Kanefusa Seito's "Ruri" rice pot from Shigaraki, a thick donabe covered in deep ruri glaze. It cooks from 1 to 5 go of rice and is ready after about 15 minutes on the heat and about 15 minutes of steaming. How to choose a donabe is covered in how to choose a donabe.

Choosing and Using Ruri-Glazed Pottery

• Choose by the color of food　Deep blue sets off the yellow of eggs, the red of tomatoes, and white tofu or white fish. Brown dishes also look sharper on blue
• Choose by light and shade　The more texture or carving a piece has, the more the dark and light blues of ruri stand apart. On flat pieces, you can enjoy the gloss of the glaze and the depth of the color
• Pair with white pottery　Set beside hakuji or kohiki pieces, the blue looks even deeper and the table comes together

Whether a piece can go in the microwave or dishwasher depends on the piece, so check the description on each product page. Everyday care is covered in caring for Japanese ceramics.

Related Articles and Terms

Getting to Know Blue Pottery

• Gosu: The Cobalt Blue Behind Japanese Sometsuke
• Sometsuke: Blue and White Porcelain, Explained
• Celadon (Seiji): The Blue-Green Glaze of Iron and Fire
• Blue Japanese Tableware: Sometsuke, Gosu, Celadon and Ruri Glaze

Regions and Everyday Use

• Seto Ware: The Kiln Town That Named Japanese Pottery
• How to Choose a Donabe | Size, Glaze, First Use and Care
• Japanese Pottery Glazes: The Main Types Explained