MOUNTING DIAMONDS WEIGHT DETERMINATION. WEIGHTESTIMATION FORMULAS  


When a stone is mounted, one cannot weigh it separately from the mounting. In such a case, the stone weight is calculated by means of special formulas. If the cut parameters of the stone differ from the conventional ones, some corrections should be added to the formulas. If stone is misshaped, the formulas yield a considerably erroneous weight. The formulas used to estimate the weight of a stone cut in one of the most common styles will be given later. To increase the accuracy of the weight determination, special computer programs, such as Diamond Calculator by Octonus Ltd. company, are used. These programs are capable of precisely calculating the weight of a diamond with known proportions.  
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Round brilliant Weight estimation = mean diameter õ heigth õ 0.0061 õ weight correction. 



Îval Weight estimation = mean diameter õ heigth õ 0.0062 õ weight correction. 



Triangle Weight estimation = length õ wigth õ heigth õ 0.0057 õ weight correction. 



Heart Weight estimation = length õ wigth õ heigth õ 0.0059 õ weight correction. 



Baguette Weight estimation = length õ width õ heigth õ 0.00915 



Trapeceidal baguette Weight estimation = length õ mean of 2 parallel edges õ heigth õ 0.00915 



The first step of the weight estimation of diamonds with an emerald, marquise, and pear cut is the calculation of the lengthtowidth ratio (by dividing length by width). This value is rounded off to one hundredth. Weight corrections should be applied for thick or extremely thin girdle, deep or shallow pavilion (crown), large culet, and significant curvature of facets in fancy cuts. The weight correction can range up to 10% of the stone weight. 



Emerald cut Weight estimation = length õ width x heigth õ coefficient õ weight correction. Weight correction coefficients




Marquise Weight estimation = length õ width õ heigth õ coefficient õ weight correction. Weight correction coefficients




Pear Weight estimation = length õ width x heigth õ coefficient õ weight correction. Weight correction coefficients
