Poor setting or polishing can lead to disappointing results in gem jewelry. Improper polishing can lead to “fuzzy” stones when improperly buffed. Unfortunately buffing does NOT enhance the sparkle of a gemstone. Much of the polishing compound that jewelers use when polishing a ring is made of corundum, which is a 9.0 in hardness. Gems finish at 8.5 can be easily damaged by corundum polishing powders.
Our supplier suggests the following. If you are having any jewelry repaired or worked on by a local jeweler, you might wish to share this with your local jeweler. In the instance illustrated here, the stone was set in platinum, but similar instructions will work for gold.
What does my jeweler need to know about setting cubics?
1. Please tell him not to use ruby powder to polish gold or platinum that is set with gem because the corundum will scratch the stones.
To polish platinum with gems, tell him to start with a brush and brown paste to cut and erase any line, then with brush also and white paste keep polishing until he gets shine, then he must use a brass brush to have it more polished and the final polish is with green paste and a lint or a chamois buffing wheel of the smallest possible diameter, but never use the ruby powder or the ruby impregnated rubber discs.
All the red or the pink discs used to polish platinum have ruby powder and are the best to polish platinum but you can only use them when they are set with diamonds.
It will take your jeweler a few minutes more in the polishing but he will not damage the stones.
2. Prongs must be well polished before final setting of the stone as it will be very difficult to polish them without damaging the stone after the stone is set.
3. If setting princess cut or other stones with sharp corners, it may be advisable to “soften” the corner on a polishing wheel. Taking away the sharp point will dramatically reduce the incidence of breakage when pulling the prong over the point. We would never do this with a stone costing thousands of dollars per carat, like a diamond, but it makes a lot of sense when setting a fairly brittle stone like a cubic zirconium.
4. Stones must be cold set for best results. Stones set with heat are subject to breakage. Be absolutely sure to inform your jeweler that stone is a gem even when dealing with a jeweler who does have experience with gems. If you do not, then you bear the responsibility for what might happen. Your new stone may LOOK like a diamond, but if set with heat and polished with corundum, neither you or your jeweler will be at all happy.
This picture is one example of the difficulties in setting a gem correctly and what it can look like when it is done incorrectly.