Some Trademarks Lose Their Luster; Some Trademarks are the Luster

A trademark or service mark can be anything that is distinctive of the source, including the luster of the the product.  Thus a trademark might be a metallic surface:

metallica pearlescent surface:


a matte surface:

mattea glossy finish:

glossya frosted surface:

frosteda sparkly surface:

glitterya shiny surface:

shinyand a reflective surface:


Whether incorporated into a product for that purpose, or a happy accident of design, any feature of a product that customers can recognize as indicating source, can be a trademark.