This name is associated with problematic and illegal use of the hallmark on non-Native material (and non-Calvin work). As always, microinlay in particular is a kind of jewelry widely faked and very commonly Asian import in orgian.
There are many threads online about the legal suits, and a thread here on the forum that will be of interest. In short, he made jewelry but his hallmark was illegally faked on or applied to other material.
https://legalnewsline.com/stories/510519779-new-mexico-ag-targets-fake-native-american-jewelry
other Google search
https://www.google.com/search?client=firefox-b-1-d&q=calvin+begay+sued
https://forum.turquoisepeople.com/t/calvin-begay-late-1990s-14k-gold-and-opal-bracelet/12226/7