PEARLS AND PEARL SHFLLS. 451 



Ao-gai-zaiTcu, mother-of-pearl work. — Pearls and niother-of-pearl consist of thin 

 laminae of carbonate of lime with a little organic substance. But while they are 

 found in concentric layers in the pearls, in the latter the lainime follow the direction 

 or trend of the shell, yet in such a way that even in flat mussel and snail shells they * 

 lie somewhat inclined to the surface. The luster proceeds from the reflection of light 

 and the iridescence or play of color from the interference of the rays reflected from 

 the projecting edges of the thin lamina? or blades and the somewhat deeper parts. 

 (The color change or iridescence of mother-of-pearl, consequently, is a phenomenon of 

 interference which inheres in the structure, and is analogous to the colors of diffrac- 

 tion spectra produced by ruling very fine lines upon glass plates, etc.) 



Furniture inlaid with mother-of-pearl is very popular in Turkey and throughout 

 the entire Orient, but particularly in farther India and China. In Japan it is used 

 mainly for decorating lacquer wares. A product of the country, called ao-gai 

 (awogai), used in thin sheets, is distinguished by its magnificent iridescence in all 

 the colors of the rainbow, and is obtained mainly from the smooth inside of the larger 

 varieties of ear shell (Haliotis japonica Reeve, H. gigantea Chemn.), called awabi. 

 A still more valuable sort goes by the name of ao-gai-magai, i. e., imitation ao-gai. It 

 is formed of lamina? scarcely 3 centimeters broad, and is said to come from the Riu- 

 kiu islands, from a kind of Nautilus. The shell of the Sazaye {Turbo cornutus 

 Chemn.) also yields mother-of-pearl. 



The polishing of the mother-of-pearl, as observed in Nagasaki, is not scientifi- 

 cally conducted, since there is no facilitation of the work such as is afforded by the 

 heavy grindstone, revolving vertically on its axis. The thick, curved outer edge of 

 the Haliotis shell is first removed up to the row of holes, by means of pincers, ham- 

 mer, and chisel; then the remaining part is ground on a fine-grained grindstone, 

 sprinkled with water, till only a thin transparent lamina remains. It is a very weari- 

 some work, and one man can polish only eighteen pieces a day. Each sheet costs from 

 2 to 6 sen, according to size and fineness. These thin sheets or plates, as well as the 

 mother-of-pearl dust of various degrees of fineness, obtained from the waste, are now 

 used by the ao-gai-shi, or mother-of-pearl workmen, for decorating lacquer wares. 



The inlaying of pearl in lacquer * is effected almost exactly as we inlay our papier- 

 mache work, the process differing only in detail. The pieces of pearl from which the 

 parts to be inlaid are cut are very thin, and can be used like tracing paper. Before a 

 work of this kind is begun, a drawing of the pattern is made on a sheet of paper; this 

 drawing is transferred to the box or tray upon which the pattern is to be wrought. 

 Little sheets of pearl are now placed over those parts which are to appear in this 

 lustrous material; the forms covered by the sheets of pearl are traced upon them, and 

 then they are removed. With a curious chisel-like knife, the pearl is next cut into the 

 desired shapes, and these are stuck by lacquer in their respective positions. After all 

 are in place, the whole surface is covered with repeated coats of lacquer, by which the 

 pearl is entirely hidden. By grinding, a smooth surface is then secured, and the pearl 

 again appears, but is now level with the general surface. The pattern is again trans- 

 ferred to the surface, having been fitted to the bits of pearl so that they may take their 

 right places. 



Besides this ra-den or mosaic work with thin sheets of mother-of-pearl, thicker 



* "Japan," by Prof. Christopher Dresser, page 362. 



