New Gem Jars Gemstone Display For Jewelry Showcases & Countertops. This is a new white gemstone display tray inserts. This insert contains 15 removable clear plastic round jars. These will hold all of your loose stones, beads and coins. Each gem jar comes with a white insert pad inside and lid. The inside diameter of each gem jar measures approximately 1" (25 mm). This insert measures approximately 7 3/4" x 4 1/4" x 3/4" (197 x 108 x 19 mm).