Marquise Diamond Weight Estimation (11.15)
Length-to-width adjustments (LWA) for weight estimation formula. The LWA is used in all marquis weight estimation formulas.
L/W ratio LWA
1.50/1.00 .00565
1.75/1.00 .00570
2.00/1.00 .00580
2.25/1.00 .00583
2.50/1.00 .00585
2.75/1.00 .00590
3.00/1.00 .00595
Marquis Formula:
Length x Width x Depth x LWA x GTA
#1 Example of formula in use:
Length measurement: 10.24 mm
Width measurement: 6.11 mm
Depth measurement: 4.75 mm
Girdle: Thick+
L/W Ratio: 10.24 divided by 6.11 (length divided by width) = 1.6759, rounded up to 1.68 to 1. Referring to the previous LWA list for marquis diamonds, notice that the 1.68 L/W ratio is closest to the 1.75/1.00 case, so this will set the LWA in the formula.
Since the girdle average was determined to be Thick+, then referring to the GTA table (p. 137), 1.035 will be assigned as the GTA multiplier in the formula. For diameter, use the width of the fancy shape, not the length, in choosing the correct column of GTA multipliers.
