Silver Circlet

A Silver Circlet is a common Circlet-class headwear available throughout the  Golden Sun series.

Basic Description by Game
In all its appearances, a Silver Circlet increases the equipped Adept's base Defense rating by 16 points. As a common item, it can be bought repeatedly from Vendors for 1300 coins each, and sold for 975 coins each.

In Golden Sun, Silver Circlets are sold in Xian, Altin, and Kalay, and can be equipped by Ivan and Mia. In Golden Sun: The Lost Age, Silver Circlets are sold in Naribwe and Kibombo, and can be equipped by Jenna and Sheba. In Golden Sun: Dark Dawn, Silver Circlets are sold in Ayuthay, and can be equipped by Karis, Rief, Amiti, and Himi.

Analysis
In Golden Sun when it can first be bought in Xian, it is a very strong and worthy upgrade to what Ivan might likely be wearing since the game's start, his normal Circlet. Afterward, if you have the surplus money after having shopped around with the other equipment at vendors, you may buy a second Silver Circlet to replace Mia's Wooden Cap. It will last until your journey reaches Kalay, where you can buy Mail Caps.

In The Lost Age, the Silver Circlet might never be bought because Jenna and Sheba will most likely already be equipped with stronger headwear: the Nurse's Cap and the Clarity Circlet. So, it is safe to say that the Silver Circlet is useless, unless you missed one of the above two items.

In Dark Dawn, Amiti will join the party with a Silver Circlet as his default headwear. A Silver Circlet is a good upgrade for Rief from whatever headwear he may have. Karis, on the other hand, can equip the stronger Glittering Tiara, which can be found in Barai Pond. By the time the player crosses into Te Rya Village, they will be able to replace all three Silver Circlets with stronger headwear Artifacts.