| Site | Category |
| universal pacific | Diamond Dealers - Wholesalers |
| UralAlmazInvest Co. LTD | Diamond Manufacturers |
| U.S. Patent & Trademark Office | Education |
| Universal Gemological Laboratory | Gemological Labs |
| Unison Gemstones Ltd. | Jewelry Manufacturers |
| Unistar Creations | Jewelry Manufacturers |
| Unistar Creations | Jewelry Manufacturers |
| Urja Creations, Mumbai | Jewelry Manufacturers |
| USA Studs | Jewelry Manufacturers |
| United Jewelry Services | Jewelry Publications |
| Underwoods Jewelers | Jewelry Retailers |
| Union Diamond Corporation | Jewelry Retailers |
| uniteddiamondbrokers | Jewelry Retailers |
| USA Diamonds.net | Jewelry Retailers |
| USA Rings | Jewelry Retailers |
| Universal Fine Jewelry | Jewelry Wholesale |
| United Parcel Service | Shipping Services |
| US Post Office | Shipping Services |