For years these garnets were sold as coming from Lake Jaco. No garnet has ever come out of Lake Jaco.
The false locality was put about deliberately, to keep competitors away from the real ground while it was being worked. It stuck. Specimens are still circulating today in old collections with Lake Jaco written on the label, and museums and dealers have spent decades untangling it. The actual source is the Sierra de Cruces range in Sierra Mojada municipality, Coahuila, first worked for these in 1994.
Two other versions turn up on labels, Sierra de las Cruces and Sierra de la Cruz. Both are wrong. Small errors, but a locality is either right or it is decoration, and a specimen with the wrong ground written on it has lost the only part of its history that cannot be recovered later.
Mineral: Grossular garnet (Ca₃Al₂(SiO₄)₃), a calcium aluminium silicate
Crystal system: Cubic
Origin: Sierra de Cruces, Sierra Mojada Municipality, Coahuila, Mexico
Hardness: 6.5 to 7 on the Mohs scale; hard, but the crystals are brittle at the edges and chip rather than scratch
Treatment: None
Dimensions: 2.97 x 2.7 x 1.51 cm
Weight: 11.72 g
You will receive the exact piece photographed.