Enter the length, width, depth, specific gravity, shape factor, and weight correction factor into the calculator to determine the gem weight.

Gem Weight Formula

The following equation is used to calculate the Gem Weight.

GW = L*W*D*SG*SF*WCF
  • Where GW is the gem weight (carats)
  • L is the length (mm)
  • W is the width (mm)
  • D is the depth (mm)
  • SG is the specific gravity (carats/mm^3)
  • SF is the shape factor
  • WCF is the weight correction factor

What is a Gem Weight?

Definition:

A Gem weight is defined as the total mass of a gemstone based on the physical characteristics of length, width, depth, specific gravity, and shape.

How to Calculate Gem Weight?

Example Problem:

The following example outlines the steps and information needed to calculate Gem Weight.

First, determine the length, width, and depth. In this example, these are 3, 4, and 2mm respectively.

Next, determine the specific gravity. The specific gravity is a measure of density, and in this case, equals 1.25 carat/mm^3.

Next, determine the shape factor and weight correction factor. These are calculated as .675 and 1.1 respectively.

Finally, calculate the gem weight using the formula above:

GW = L*W*D*SG*SF*WCF

GW = 3*4*2*1.25*.675*1.1

GW = 22.275 carats

FAQ

What is specific gravity and how does it affect gem weight?

Specific gravity (SG) is a measure of the density of a gemstone relative to the density of water. It affects gem weight by determining how much the gemstone weighs in relation to its volume. A higher specific gravity means the gemstone will weigh more for its size.

Why are shape factor and weight correction factor important in calculating gem weight?

The shape factor (SF) and weight correction factor (WCF) are important because they adjust the gem weight calculation to account for the gemstone’s shape and potential irregularities in its form. These factors ensure the calculated weight is more accurate for non-standard shapes and sizes.

Can the gem weight formula be used for any type of gemstone?

Yes, the gem weight formula can be applied to any type of gemstone, as long as you have the necessary measurements (length, width, depth) and values (specific gravity, shape factor, weight correction factor) for the specific gemstone you are calculating. Different gemstones will have different specific gravities and may require different shape and weight correction factors.