Each specimen will be tagged as MM, TN, Miniature or Cabinet. For larger specimens, actual dimensions and sometimes weight will be included in the description. If a specimen tagged as MM or TN is not provided in a box, that will be stated.
MM = Micromount. This refers to the size of the box that the specimen is in, usually 28x28x20mm but may differ if a different box. These specimens invariably require magnification and illumination to appreciate.
TH = Thumbnail. Again, this refers to the size of the box, rather than the size of the specimen. It will usually be a larger matrix specimen, too large for a micro box, and may still require magnification and illumination to appreciate. Thumbnail boxes are usually 40mm cubed or thereabouts, again depending on the style of box. In the US, the term Thumbnail is generally used for competition specimens that have thumbnail-sized crystals, and that still fit into a thumbnail box.
Miniature. Specimens that measure approximately 30 to 60mm in the longest dimension.
Cabinet. Specimens that are larger than 60mm in the longest direction.