The Table Percentage Ratio Method 5.26

The Table Percentage Ratio Method (5.26)

The Table Percentage Ratio Method relies on your perception for comparing distances for table size estimation. Under 10x magnification, draw an imaginary line from the girdle, bisecting the star facet and extending it to the center of the table, directly above the culet. Divide the imaginary line into two pieces where the edge of the table begins. In this case the edge of the table is at the mid-point of the star, not the meeting point. Compare the two lines, mentally calculating their ratio. The easiest and most obvious ratio would be 1:1, for which the divided imaginary line shows equal distances.

The following is a list of ratio examples with their corresponding table percentages:

1:2­ 72%­
1:1.75­ 69%­
1:1.5­ 65%­
1:1.25­ 60%­
1:1­ 54%­

Many times you will encounter an off-center culet and your imaginary line will have to be altered slightly or you may have to tilt the stone slightly to center the culet. 

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