Trinkets provide Spirit, Skill Evasion, and Resistance boosts. The 3 most common and powerful trinkets are obtained from Jade Exchange Girl in Custom Sunstream [212, 92] for Welkin Green Jades. To upgrade, find Elder of Arcaneness in Jadeon. He has multiple recipes in his Shop (pages 2-4). Check out Crafting to learn more.
Note: Crafting trinkets have a chance to fail, simply try again. Gold leaves can be obtained at Shady Dealer.
Once you've refined your desired Trinket to level 9 head to Custom Sunstream to purchase the following items: Jade Scroll • 10 (1000 Monkey Coins), Jade Scroll • ★ (2000 Monkey Coins), and Jade Scroll • ★ ★ (3500 Monkey Coins). To continue refining to Trinket • ★ ★ ★ III you need to go to the Shady Dealer and from the Rare Item Exchange/Special tab buy Trinket Evolution Ticket ★ (2000 Heaven Dragon Seals). You need 3 Trinket Evolution Ticket ★ to receive Trinket Evolution Ticket ★ ★ and nine to exchange for Trinket Evolution Ticket ★ ★ ★. Upgrade these at Taja.