They are interseted in recovering anything they can, and exploring the wreck. Gold and jewels would be hard to come by as they are buried in the rubble of the stateroom floors and scattered about in the debris field. RMS most likley doesn't allow you too keep items recovered. Unless you bought them at an auction.

In otherwords they are interested in anything they can find, including missing things, that floated out of the ship during the sinking, or got destroyed in the breakup, or are laying in the debrid feild or ship covered by sand and rubble, or got destroyed due to underwater preassure or bacteria. Some include the:
Foward Grand Staircase Cherub
The Lounge Electrolier
The FGSC Candelabra at the D-Deck Landing
Light Fixture Glass Bowls
Stained Glass Window Fragments
The FGSC and Aft Grand Staircass Baulstrades
Probably Gone, But the FGSC and AGSC stairs
The FGSC and AGSC Dome fragments
And many other items.

Precise items are also gone and like the Rubaiyat have not been found.

Hope this helps.
Matt Simons