Tools of the Trade
In Geruto Town, the Gerudo standing outside the closed jewelry shop is in need of some help. Speak to Isha and you will learn that she is having trouble getting inventory together to reopen her shop. She will need 10 pieces of Flint. You can find Flint by breaking the black ore stones all around Hyrule, especially near mountains.
Hand the Flint over to her and she will then let you pick a headpiece for free. Ruby, Sapphire, or Topaz, it is entirely up to you. Afterwards, if you bring her jewels, she will only charge you a labor fee instead of full price to buy your very own jewelry gear. Note that jewelry gear still takes up a full spot. For example, the Amber-based earrings cannot be worn in tandom with a helmet. They still provide full benefits compared to helmets.