www.925-1000.com

I'm trying to decipher the marks on the back of this cross I acquired from my aunt's estate. I know she received this from her sister who traveled in Mexico and SW USA in the late 50's and early 60's. It has a 3D effect and is inlayed with (possibly) Abalone. The inlay has that green/blue pearly shimmer. The markings say from top to bottom: "Sterling", "Taxco", "MT" & "925". I think I'm pretty clear on everything except the "MT". Was that the maker? Was someone trying to pass this off as a Margot de Taxco piece to the tourist trade since it's not her marks? The chain looks original with some nice detail work on the links. Any ideas out there as to the maker? Thanks gang!
http://fessheadsfotos.shutterfly.com/pictures/9#9
http://fessheadsfotos.shutterfly.com/pictures/9#10
http://fessheadsfotos.shutterfly.com/pictures/9#11

Margot pieces are usually signed Margot de Taxco so MT wouldn't be trying to be her, her full name was Margot Van Voorhies Carr. MT is probably the artisans initials but it's not noted in the hallmark book.