Welcome, OmegaGrey,
Lots to discuss here! Can you give us a better photo of the dark pearls? What are the sizes of the necklaces? The white pearls show nice luster, but cannot tell much else from the photos, regarding blemishes, or anything about the dark pearls.
Most (yes, I said most) women I know would love to receive either or both of these necklaces as a gift. I'm guessing that the price for these are in the 4 figure range. Are they graded? Where are you purchasing these from, a wholesaler, a store? Are you buying online or in person? Have you any knowledge or experience with pearls before? Are the dark pearls Tahitians?
No matter what you are being told by a salesperson, it will be difficult for you to recover 100% of your investment, much less make a profit on these, no matter how beautiful, more likely less than 50%.
I hope you will share much more background information with us.