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It must be remembered that different markets may not value the same quality stones at just the same price. There may be more demand in New York for a certain size and color of stone, which may give it a higher value than that placed on it in, for example, London. But it can be said that, among diamond dealers, the value of a stone can be assigned to within a very small limit at a given time.
Stones mounted in a piece of jewelry should be examined very closely since a skilful mounter can apparently improve shape and color as well as hide certain faults. Reflected light from the metal will fall on the diamond and influence its appearance. Platinum and palladium are now more often used than gold since the last reflects a yellow color. No metal should be left close behind the culet for this reason, although in old pieces of jewelry diamonds were often entirely enclosed in the setting, apart from the upper part of the stone. Such stones are often improved by resetting, although a “closed in” setting sometimes hides a rough edge, bad shape, or other imperfections. It should be remembered that square cut stones, or those other than the brilliant cut, are difficult to estimate for weight, and even experienced dealers make mistakes. So extra care must be taken in such instances.