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Pellucid stone6/12/2023 This is turbinated into an edge with a smoothnesse of six sides, and it is sometimes found in the bignesse of a filberd but this is not found grow∣ing in gold. An Indian one, which hath some affinitie with Crystall. In it, and so rob the stone of the glory of its beautie and value, and the artist of his hopes by frustrating him of his endeavours.Īnselmus Boetius saith, that he saw a Topaz in this manner changed, (which is better then an other stone for this purpose because of its hardnesse) and it was in weight seven Ceratia, that is, twenty eight grains, which was valued at three hundred Florens, or Crowns.ġ. And if by this first operation it be not perfectly deprived of all its colour, then the same work must again be begun, and carried on as before by severall degrees of heat: and if need be, it may be iterated: ever observing this, that as it must be heated by a graduall increase of the fire, so likewise by a graduall decrease of the heat the fire must be extinguisht: for the over-sudden heating or over-sudden cooling of the stone may cause a crack Jewellers and judicious artists well know in what space of time, by the continuance of this great heat, any such ex∣cellent gemms may be deprived of all their colour which colour of the gemm, so soon as they do con∣ceive it is vanisht by the power of the heat, then do they extinguish the fire by degrees, till there be no more heat left. calx viva, and the filings of steel bury the stone in them, or in either of them, then overwhelm them w th a fire at some distance frō them, that the stone by degrees may grow hot then increase the fire, and the colour will vanish. The colour of those gemms which are fit for this use, may by the heat of fire be thus taken away: R. A True Diamond may be adulterated or counter∣feited with a Saphire, or with an orientall Ame∣thyst, or with a Topaze, or with a Chrysolite, and by all stones that are hard and transparent, and which may be deprived of colour.
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