The Smithing ring is made by right-clicking the uncharged ring and selecting "Charge" within the Smithing skill plot area of the Clan Citadel, which requires a tier 3 Citadel. The ring requires a Smithing level of 40 to be charged. It gives 150% Smithing experience until you have gained a certain amount of experience, determined by your level and the tier of the Smithing plot, after which it crumbles to dust. A new uncharged ring can only be obtained after this one has been used up.
The ring stacks multiplicatively with Goldsmith gauntlets when smelting (2.5*1.5 = 3.75 times normal experience), yielding 84.3 Smithing experience per gold ore. However, it only stacks additively with the Goldsmith gauntlets when superheating (+50% from the ring plus +150% from the gauntlets = +200%, or 3 times normal experience), yielding 67.4 Smithing experience per gold ore. The smithing ring and sacred clay hammer will not stack when smithing regular bars into items, however, they will when making dwarven burial armour as long as the ring is equipped or in your inventory and the sacred clay hammer is in your inventory. The sacred clay hammer bonus is used in addition to the clan ring bonus.
Since clan rings only work with normal training methods, this ring does not work for creating bars in the Blast Furnace. However, it does apply to work done at the Artisan's Workshop, including activities that would normally not be counted by a sacred clay hammer.