L/W Short for Length/Width

What does L/W mean and what is it used for?

L/W is short for Length/Width.

It is a mathematical ratio used in designing and determining the proper pattern(s) for cutting rough. L/W is one of the most important things to understand in almost all stages of rough buying and cutting.

Here is how it works. First you need to measure your rough, in millimeters usually. How long? How wide? How deep?

Note: You do not need the depth for the L/W ratio, but it will be needed later in your design selection.

Now take the length of your stone (rough you are picking a design for) and divide it by the width or your stone. You will end up with a figure something like this:

10mm/8mm = 1.25 L/W

It is that easy. If your stone L/W is shorter than the design you want to cut, you need to pick a shorter design. You can cut rough off but you cannot add it on. Pick the L/W and design that most closely match each other.

Below is a chart of the standard L/W ratios, you will need to round your stone down to the nearest one, unfortunately we cannot add more stone. Basically you can now select any design you like that is a match for your stones L/W or a little smaller if you do not mind cutting a little finished weight off.

Ovals / RectanglesPearsMarquise
3 x 5 = 1.673 x 5 = 1.672 x 4 = 2.0
4 x 6 = 1.504 x 6 = 1.502.5 x 5 = 2.0
5 x 7 = 1.405 x 7 = 1.403 x 5 = 1.67
6 x 8 = 1.335 x 8 = 1.603 x 6 = 2.0
7 x 9 = 1.296 x 9 = 1.504 x 8 = 2.0
8 x 10 = 1.257 x 10 = 1.435 x 10 = 2.0
10 x 14 = 1.406 x 12 = 2.0
12 x 16 = 1.337 x 14 = 2.0
13 x 18 = 1.38

ratio = length divided by width
length = ratio times width
width = length divided by ratio

Note: You can cut a non-standard L/W if you have a design or want to create a design, but remember that most standard jewelry settings will not work on this stone if you do.

About the author
Jeff R. Graham
The late Jeff Graham was a prolific faceter, creator of many original faceting designs, and the author of several highly-regarded instructional faceting books such as Gram Faceting Designs.
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