Art Mart: Deathless design

Art and design blend in the salerooms this week. For the very rich, Christie's natural history sale next Tuesday (2.30pm) offers a Turkish album, from about 1725, at an estimated pounds 100,000-pounds 150,000. It contains exquisite watercolours of 42 cross-bred varieties of tulip - all now extinct. The Ottoman court in Istanbul was gripped by tulip mania at the time - nearly 100 years after the Dutch and English crazes.

This glass "handkerchief" vase from Murano, Italy, from about 1950, looks more like a modern tulip than a hankie. The shape has become fashionable. The technically accomplished latticework adds value - as does the highly collectable date. Estimate pounds 500-pounds 700 in Christie's London sale of British and Continental decorative arts, tomorrow (10.30am).

Designer buttocks? Or just a rounded riposte to Cubism? This cheeky 1927 Art Deco oil on canvas by Walter Krehn, entitled Curtain Call, is expected to fetch pounds 1,000-pounds 1,500 in the same sale.

Not exactly buttock-friendly is this jokey, giant-sized tilting chair, designed by Alessandro Mendini for trendy Italian furniture makers Alchimia in 1983. A unique piece, clad in mirror glass, it's an expensive joke, with an estimate of pounds 15,000-pounds 20,000, among 127 lots of Italian avant-garde design in Sotheby's sale "Design Since 1935", tomorrow at 10.30am.

Much cheaper (even a medical student might afford it) - is Nazareno Noja's plastic-coated female silhouette, apparently gynaecologically inspired, also from Alchimia and dated 1976. It is estimated to reach pounds 200-pounds 300 in the same sale.

An in-joke among the gem set: corny jewellery by respectable makers. This daft duck brooch, by Piaget, of the late Sixties has an emerald eye and carved coral beak and feet. The estimate is pounds 850-pounds 950 in Christie's South Kensington's sale of 20th-century jewellery, next Tuesday at 2pm.

Much older, cheaper and not half so silly: a recumbent, blue-and-white Chinese porcelain cat from the 18th century, designed as a translucent night light with illuminated eye sockets. It's estimated to sell for pounds 600-pounds 800, the last lot in Christie's South Kensington's sale of oriental ceramics and artworks, Thursday at 10.30am and 2pm.

Christie's: 0171-839 9060; Christie's South Kensington: 0171-581 7611; Sotheby's 0171-293 5000.