Solid 14k open heart pendant with tiny crystal necklace

Solid 14k gold heart pendant with tiny crystal on dainty solid 14k gold box chain. I have no idea what the crystal is. Excellent used condition. There's some light normal wear to the pendant. The chain is a little crooked in some places but you can't tell while wearing the necklace. Chain is about 20" long. Pendant is about 17mm across x 15mm tall. Questions &/ offers welcome! (lowballs ignored)