The art of glass shewing how to make all sorts of glass, crystal and enamel : likewise the making of pearls, precious stones, china and looking-glasses : to which is added, the method of painting on glass and enameling : also how to extract the colours from minerals, metals, herbs and flowers ... : illustrated with proper sculptures / written originally in French, by Mr. H. Blancourt, and now first translated into English ; with an appendix, containing exact instructions for making glass-eyes of all colours.

CHAP. CXLV. Another Way of turning the White Sapphire into a true Diamond.

HERE follows another noble Method of convert∣ing the Sapphire into a Diamond, which will be easier to those who have not the opportunity of a Glass-house Furnace, for it may be done with a Wind Furnace, in twelve Hours time.

The Materials we are going to shew, which are u∣sed in this Operation, will at first seem very expen∣sive; but if you consider it diminishes not, but you find it all again, you'll easily see, that the only Ex∣pence is in the Fire.

You must therefore begin, by well wrapping your White Sapphire, in a thin Iron Plate, that it may be easily managed. Then take fine Gold, purified by Antimony, to the highest, put it in a Crucible in a Wind-Furnace, melt it, and when it has a good fine Gloss, put the Sapphire, covered with the Iron-Plate, into the Bath, so that it may float on the Gold on

every side; then give it a strong Fire for twelve Hours, so that the Gold may be all the while in Fu∣sion. Take out your Sapphire with a little pair of Tongues, shaking out the Gold that may chance to stick in the Leaf-Iron; then let it cool by the Fire gently, for fear it should break. Being cold, take away the Plate or Leaf of Iron, and you'll have your Sapphire of an admirable. Beauty, it having acquired by that coction all the Qualities and Perfections of the Natural Diamond. Polish it at the Wheel, and Work it.