| Site | Category |
| Open Alias Corp. | Appraisers |
| Open Alias Corp. | Appraisers |
| Occigems Inc., Newyork | Diamond Dealers - Wholesalers |
| Omnia Diamonds | Diamond Dealers - Wholesalers |
| Oscar's Jewelry Design | Diamond Dealers - Wholesalers |
| Occigems Inc., Newyork | Diamond Manufacturers |
| Ovadia Diamond Company | Diamond Manufacturers |
| Online Diamond Buying | Education |
| Opals Direct | Gemstone Dealers |
| Oscar's Jewelry Design | Gemstone Dealers |
| Occigems Inc., Newyork | Jewelry Manufacturers |
| Online Jewelry Superstore | Jewelry Manufacturers |
| Open Union Industrial Ltd. | Jewelry Manufacturers |
| Oreficeria Leone | Jewelry Manufacturers |
| OroStyle.com | Jewelry Manufacturers |
| Oscar's Jewelry Design | Jewelry Manufacturers |
| One of a Kind Angels | Jewelry Retailers |
| Online Jewelry Store | Jewelry Retailers |
| Orange | Jewelry Retailers |
| Osborne's Jewlers | Jewelry Retailers |
| Oscar's Jewelry Design | Jewelry Retailers |
| Oslunds Jewelers | Jewelry Retailers |
| Olympic Mountain Gems | Jewelry Supplies |
| Orostudio Italy | Jewelry Supplies |
| Occigems Inc., Newyork | Jewelry Wholesale |
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