Why trust sending off my diamond for possible sale

[flakeee]

Why should I trust sending my diamond off to Lippencott's for sale/appraisal? What If I decide not to accept the offer? What would stop them from sending a lesser diamond back to me in it's place?

 

[Garry H (Cut Nut)]

Professionals work a liftime (sometimes more than 1 generation) to establish a business which can be bought to nil value by one shady deal.

Is your diamond worth enough for someone to retire on the proceedes filthy rich ?