Are Tahitian or south sea pearls the most expensive pearl?

It is in the outcome of this 1 lamellar shape that pearl shells admit of being split into laminae for the handles of knives, for counters, and for inlaying. Splitting, but, is at risk of destroying the shell and is consequently averted as plenty as feasible. The distinctive parts of the shell are selected as almost as possible to in shape the required purposes, and the excess of thickness is bumped off at the grindstone. In preparing the rough pearl-shell, MOP Handicrafts the square and angular pieces are reduced out with the regular brass-lower back noticed, and the circular pieces, which include those for buttons, with the annular or crown-noticed, fixed upon a lathe-mandrel. The pieces are next ground flat upon a moist grindstone, the brink of which is turned with a number of grooves, the ridges of that are much less at risk of being clogged than the entire surface, and as a result, grind greater fast. If the stone is wetted with soap and water it is less liable to be clogged.

The pieces are completed on the flat side of the stone and are then equipped for inlaying, engraving, polishing, c. Cylindrical pieces are cut out of the thick a part of the shell, near the hinge, and are rounded at the grindstone preparatory to becoming within the lathe. The finishing and sprucing are defined within the third extent of Mr. Holtzapffel's high-quality paintings on " Mechanical Manipulation" Counters,. Mother of Pearl Inlay in Marble silk-winders, c, are smoothed with Trent wk sand or pumice-stone and water on a bufl wheel or hand-polished, and are finished with rotten-stone moistened with sulphuric acid, which develops finely the striated structure of the shell. For inlaid works the surface is made flat by way of submitting and scraping ; then pumice stone is used, and after this putty-powder, each on buff-sticks with water; and the final polish is given with rottenstone and sulphuric acid, except tortoise-shell or a few different substances liable to be injuriously affected by the acid be present within the inlay. In grew to become works great emery paper, rottenstone and acid or oil are used. The pearl handles for razors are slightly riveted collectively in pairs, then scraped, sand-buffed at the wheel with Trent sand and water; thirdly, gloss-buffed at the wheel with rottenstone and oil, or now and again with dry chalk rubbed at the same wheel; and fourthly, they're handed up, or polished with dry rottenstone.