I do not understand the 'mm' thing. I have been trying to match a garnet cabochon to a garnet oval toggle so I can make a matching pendant. Help?
The term "mm" refers to millimeters which is a metric unit of measurement. Many items within the jewelry making industry are measured in millimeters due to how precise one can get with this unit of measurement. You may want to use a caliper or slide gauge to get the most accurate measurement. Our handy "Metric Conversions" chart is especially helpful as well.
Also, when trying to match cabochons and cameos to the clasp you are using in your design, I recommend purchasing more than one cabochon. This will allow you to color match your gemstone cabochon to the gemstones used on your clasp.