I prefer to coat mine with the same Cashew lacquer used by Keith in his videos. I have found it in different places in the US.
Here is one and Here (where I get mine).
I find this is the very best sealer for any stone that will spend any time in water. I don't find it toxic or objectionable in any way except you need to thin it with Lacquer thinner and do a couple of thinner coats and let dry for a couple of days but it is a great sealer. better than anything else I have used.
I find Shelac does not hold up to repeated soakings and extended use. It is great for wood but I would not trust my $$$$ stones to it.

Just my 2¢. Keith's video is great BTW.