Many people glue their cubic stones back in with super-glue. But super-glue is messy, and get one speck on your pendant, chances are that it will be ruined. Super-glue also tends to cloud the clear stones, thus affecting the stone's clarity. We have used an effective alternative to super-glue when gluing stones back in place. Enter clear silicone. The advantage of clear silicone is that it will not ruin your pendant because it is forgiving, even if you get the glue everywhere,  It CLEANLY rolls off like rubber. Usually available at Wal-Mart, auto parts stores, home improvement stores, etc.