Where is a good place in Switzerland to sell a diamond necklace

Hello , I would like to know where would be a good place in Switzerland to sell a used diamond necklace . I don't really know how much it could worth now or the karats , just that is a 14k gold , which it costed a good amount of money in US . Would it be a pound shop or diamond buyers  somewhere who could give me a fair value on it ?  Thank you so much !!  :)

Sorry , above I meant pawn shop.