The Sapphire Glass Hand is an item that can be sold to the Museum for 15,000 Coins. It can be made with Level 12 Crafting with 20 Glass and a Sapphire. Because a Sapphire can be sold the NPC Shop for 10,000 coins, which is also the Minimum Price on the Player Market, you can gain a one-time additional 5,000 Coins from the Sapphire by making the Sapphire Glass Hand.
After adding the Sapphire Glass Hand to the Museum, it can be examined to show the following message:
The hand shines as you observe it from different angles.