Late Georgian / Early Victorian. So 1830s, maybe? Glass panel was meant to be opened and braided hair added underneath, but none was ever added - looks like the original grosgrain-type fabric placeholder is still there. Mint condition hand engraving on both sides. Notice the little (non-functional) "latch" on top! 1" tall including the chain it hangs from, 5/8" wide. Looks to be never worn! Testing 14k (likely 15ct).