As of September 9/23/2015, no live official trademarks were found on USPTO.gov for the exact term
Best of all, it is short and contains the word Ruby -- what's not to like about that?
In addition, on its own merit, Rubyr would be a great name for a startup, perhaps a jewelry and/or mineral business.
Without parsing, this domain is pronounceable and ready for branding your gem-type business.
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