See https://www.patheos.com/blogs/danpeterson/2016/11/the-book-of-mormon-and-an-indigent-jeweler-named-snite.html
Then a jeweler named Snite comes forward:
Finally an indigent jeweler named Snite pointed out that since the stone was still available for examination the answer to the question of whether it was a diamond or not had absolutely nothing to do with who found it, or whether the finder was honest or sane, or who believed him, or whether he would know a diamond from a brick, or whether diamonds had ever been found in fields, or whether people had ever been fooled by quartz or glass, but was to be answered simply and solely by putting the stone to certain well-known tests for diamonds. Experts on diamonds were called in. Some of them declared it genuine. The others made nervous jokes about it and declared that they could not very well jeopardize their dignity and reputations by appearing to take the thing too seriously. To hide the bad impression thus made, someone came out with the theory that the stone was really a synthetic diamond, very skilfully made, but a fake just the same. The objection to this is that the production of a good synthetic diamond 120 years ago would have been an even more remarkable feat than the finding of a real one.
You probably see the problem with this allegory. In the case of the Book of Mormon, there is no diamond, i.e., nothing to examine. No, a closer parallel to the Book of Mormon would be a farmer who claims he had found a diamond but could only produce a drawing of it. Then experts might opine on the degree to which the drawing looked like a drawing of an uncut diamond, but most would say that they were unable to say much about what the farmer had found without being able to examine the uncut diamond itself.
We can set aside the issue of how the farmer claimed to find the diamond. If he could not produce the diamond for examination, and also claimed an angel had helped him locate it, only to take it away, then what are experts likely to say? Those who are very restrained might simply refuse to opine on what they cannot examine with their own eyes, hands, and instruments.