Multi colored stone encased in sterling?

Looks authentic but I’m not sure. It is a very long necklace with turquoise and other beads. The ivory colored stone is on both sides. Can anyone identify the stone or perhaps its origin? Absolutely no markings. I’ve attached a few pictures. Thanks so much,

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<img src=/uploads/db1846/original/2X/1/1f78b484ffc2e2557b3e5d8404a7a5336a83a719.jpg">

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