Well, let's put it this way. This necklace that I made with NO diamonds I sold for retail $2,500. It's triple strand with 14k gold clasp, hand knotted on 100% silk. I would have to say that yours is going to retail for a lot more with the diamonds. Plus, I priced my piece a little lower than I probably should have given the size of the pearls.
The larger size pearl, the greater value (my necklace uses 9-10 mm). Are they natural or cultured (guessing cultured...most are), freshwater or saltwater? There are all kinds of things that determine value.