They are legit. However, there's settings are a bit weak. Just be weary of the 47th jewelers. Especially ones with the HUGE stores and people outside bugging you to come in. STAY AWAY

They will definately rip you off.
The guys at David S. will first give you a 30 mins lecture on diamonds, and they'll show you some rough diamonds, etc. They'll spend some time with you before they whip out the rocks

Unlike the other places where they shove rings up your... you know what
If you have questions about David, let me know.
Good luck,
Sam