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PRECIOUS STONES.

blue: cinnamon-coloured, salmon, or puce diamonds are also much esteemed. But pure diamonds, without flaw or tint of any sort, are those which are regarded as coming up to the market standard of excellence, and are spoken of as of the "first water." But even under this designation there is room for considerable diversity of quality, and consequently of price. And there are occasionally met with stones of such exceptional purity and beauty that the ordinary rules of valuation applicable to stones of the "first water" do not hold good. This observation, of course, refers to cut stones, that is, to well-proportioned brilliants. Such a stone, weighing but 1 carat (3·17 grains), might fetch £30 at a time when a first-water brilliant of the same weight would not realise above £20. In fact, specimen stones, like exceptionally large stones, cannot be said to be amenable to any precise rule of valuation. The value of the diamond increases in an increasing ratio with its weight up to stones of moderate size, beyond which no rule holds good. Assuming a first-water brilliant of 1 carat to be worth £20, then an equally fine 2-carat stone would fetch £60, or £30 per carat. Formerly the value of the larger brilliants increased so rapidly with their weight that a stone of 10 carats was worth over £200 per carat. But since the South African diamond fields have been extensively worked, large stones have been found in greater abundance, and have not maintained their relatively high prices.

In the preceding paragraph brilliants of the first water have been considered, but it should be added that the diamonds used in ordinary shop-jewellery, being either dull, flawed, or "off-colour," possess small market value. Reference may here be made to a trick by which the yellowish hue of a diamond may be temporarily masked. The back facets of the stone are lightly rubbed with a violet-blue wax pencil and the colour distributed by means of a bit of soft paper. The stone is then returned to its