Vasu

Vasu is a jeweler from both Oracle of Ages and Oracle of Seasons. He facilitates most the services associated with Magic Rings, including appraisal and storage. His two pet snakes are used to transfer rings from one game to another via a "Fortune Link". His shop can be found around Horon Village in Oracle of Seasons, while Lynna City holds is residence in Oracle of Ages. Regardless, the shop looks almost identical in both games, both exterior and interior included.

Appraisal
Magic Rings with unknown properties can be brought to Vasu for appraisal, revealing the rings' true potential. The first appraisal in each game is free, but every subsequent appraisal costs a few rupees. If Link already possesses a ring identical to the one he just paid to be appraised, Vasu will offer to purchase it. It costs 20 rupees to appraise a new ring, but Link receives 30 rupees for rings he sells to Vasu.

All appraised rings are automatically held by Vasu, as Link can only carry a few depending on the size of his Ring Box. Link can return to the Magic Jeweler's shop to exchange rings in his box for ones Vasu is holding, or vice versa.

Fortune Link
Two Game Boy Colors, not Game Boy Advances, can be connected with a Game Link Cable. By connecting Oracle of Ages and Seasons in this manner, then talking to the blue snake of Vasu's shop simultaneously in both games, a Fortune Link can be performed. Fortune Links give both games a new Magic Ring to be appraised, but a Fortune Link will not work with the same two games multiple times in quick succession, on Game Boy Advances, or with the same two games (two copies of Oracle of Seasons or two copies of Oracle of Ages). No rings can be obtained exclusively through this method.

Obtaining Rings
Most Magic Rings which can be obtained with a Fortune Link are fairly common, and can also be obtained through a Gasha Nut or by bumping into Maple. Only twenty of the total sixty-four rings can be found with a Fortune Link. Thirty-one rings can be obtained from Maple or a Gasha nut. One ring can be obtained either from a Fortune Link or from a task. The other thirty-two can be obtained from completing a task (opening a chest, completing a game or quest, etc.).

Rings can also be obtained from the Treasure Chest Game.

Trivia
As a character, Vasu might have been inspired from Hindu Deities of the same name, if only due to namesake and his Middle-Eastern style.