All of our Tungsten rings are Cobalt Free and hypoallergenic.
我们所有的钨钴环是免费和低过敏性。
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This Quality Tungsten Ring is Cobalt Free to avoid allergies and it has the Carbide to make it Scratch Resistant.
这个品质钴钨环是免费，以避免过敏，而且有硬质合金，使其耐划痕。
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A series of cobalt platinum tungsten alloys were deposited with sodium tungstate and cobaltous sulfate as the main salts and citrate as the complex agent.