What does ob 14k mean?

Grandmas Platinum and sapphire bracelet looks priceless, but the OB 14k means that it is 14k gold "overband" or later known as electroplate or 14k GP for Gold Plated. Crushed i set out to prove that at least we had sapphires. Alas, a pin scratched the gem which should be second only to diamond in hardness. Sorry to disappoint you, but your jewelry is old, but also not worth a lot, aside from sentimental significance.