| Business | Phone |
| Washington Gem & Mineral Co 640 E Diamond Ave # B, Gaithersburg 20877 | (301) 963-0200 |
| Mikita International Inc 16801 Oakmont Ave, Gaithersburg 20877 | (301) 548-0076 |
| K K Gems & Beads Inc 615 S Frederick Ave # 300, Gaithersburg 20877 | (301) 330-7320 |