I recently purchased two carnelian cabochons in a local store. One is oval, about 1" L x 3/4" at the widest part. The second one is 1/2" L x 3/8" at the widest part. How do I convert these to mm sizes? I'd like to purchase a pendant and ring setting to put them in.
I would recommend purchasing a caliper to measure your cabochons. It will measure the stones accurately in millimeters (mm's).
When purchasing mountings and settings for the stones, be sure to have your measurements handy and inquire if the stones should be smaller than or equal to the measurements indicated for the setting.