Hardened cobalt alloys for forming jewelry, including finger rings as well as methods and processes for producing such alloys. In one illustrative embodiment, such an alloy can contain cobalt in an amount of from about 35 wt % to about 65 wt %, in combination with chromium in an amount of from about 16 % wt to about 32 wt %, and molybdenum in an amount of from about 8 wt % to about 31 wt %. Aluminum, silicon, boron, titanium, and other hardness enhancing materials may also be present. Hot investment casting may be used to form items from the alloys, which may then be shaped or polished to a final form. Annular finger rings constructed from these materials may have a white appearance similar to white gold or platinum, may have increased resistance to scratching compared to traditional cobalt chromium rings, and may be easily be removed by cracking in an emergency situation.