The Gem Tang is really not that great looking in the first place.
As standard healthy purple tang is better-looking IMO.
If you want something more exotic looking for a reasonable price the Achilles tang (though quite delicate and difficult to keep) is very colorful.
Whereas the solid (and plain looking) black Tang is $1,500+ go figure.
Is amazing how much hype is generated by mere "rarity" in this hobby.