Page:A treatise on diamonds and precious stones including their history Natural and commercial.djvu/49

 met with in general trade, and are variable in price, as the dealers exact more if they know that such stones are wanted, than they would in the regular course of business. The prices may be said to vary from £180 to £200.

of six carats, as before-stated, are not common; they are suitable for centre stones of expensive necklaces, and single stone rings: if perfect and well-shaped, they sell for £230 to £250, or more.

For estimating the value of peculiarly fine diamonds, there is no fixed standard; the rule already published may, however, serve as a sort of guide.

Diamonds, selected as fine, and well formed for cutting, may be estimated as follows: Square the weight of the stone, multiply the product by two, and the result will be the value in pounds ster-