To deposit a gem, just use it with the gem bag or left-click the bag to store any uncut gems in your inventory. You will get the message: "You add the gem[s] to your bag." Players may only own one gem bag at a time.
The Gem bag can be used when buying gems from TzHaar-Hur-Lek. The bag can also save inventory space when collecting gems dropped by monsters who drop gems frequently, such as goraks, abyssal demons, and many Slayer monsters. Additionally, it can be used to store gems gathered when mining regular rocks and Motherlode ore veins, cracking a wall safe in the Rogues Den, and so forth.
The Gem bag is also useful when crafting jewellery. You can have the gem bag and a number of gold ores/bars in your inventory (saving at least 1-2 space for gems to be withdrawn). Walk to a furnace, withdraw as many gems as you want, cut them with your chisel (since the gem bag does not store already cut gems), craft them with your gold bars, and repeat.
The gem bag can also be used while doing Muddy key runs into the wilderness. The Muddy chest yields one uncut ruby every time it is opened. Therefore the gem bag can allow a player to carry back much more loot from the chest.
Storing gems in the bag saves bank space.
You can sell your Gem bag back to Percy for 80% of their original cost.
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