This 18 inch collar-style necklace is six strands of freshwater pearls artfully twisted together. Nestled within the twists are several 4mm "black diamond" Swarovski crystals. The clasp is a hook and eye clasp of 0.925 sterling silver.
What is a cultured pearl?
Instead of allowing the oyster or mollusk to make a pearl on its own--a process than can take decades--a tiny foreign object is placed in the tissue of the oyster. It coats the offending object with nacre, eventually forming a "pearl". It is closely monitored until it is ready to harvest. 99% of today's pearls are cultured.
For further reading: Cultured Pearl