How to Correct Faceting Mistakes

by Donald Clark, CSM IMG

Missed Index One of the most common faceting mistakes we make is not setting the index correctly on our faceting machines. If you miss it by just one notch, it’s enough to throw off the entire design. Here’s the diagram for a meetpoint oval being cut with a 64 index gear. You should cut the shaded facet at 44.7° and I 7, (followed by I 25, 39, and 57.) Now, say you make a mistake and cut it at I 8. If so, you should cut symmetrical facets all the way around, using indexes 24, 40, and 56. How do you determine that? The Solution Simply add and subtract the proper number from your top and bottom index settings. This index gear has a setting of 64 (or 0) at the top and 32 at the bottom. We started with 8 from the top. Therefore, subtract 8 from 64 and you get 56. Add and subtract 8 from 32, the bottom center, and you get 24 and 40. Your gem will look like this (with the new facets shaded).