Pantone color is the most used color system for metal products. It is always used for enamel colors--the color painted on the recessed areas of the metal item surface.
However, in metal gift industry, the paint is mixed according to the pantone color system. As it is handmade, the painted color can not be exactly the same as Pantone color system, and can not be always the same, but can be as closer as we can. That is why the colors in reorder may be a little different from the previous order, a little darker, or a little lighter.
Below is the most commonly used color chart. Refer to this if you do not have any ideas about which color is suitable for your logo or designs.