Chrome is the most commonly used deposited materials for graticules production. The reasons are that it very resilient and tough which helps the graticule manufacturing process in achieving high precision patterns. The reflection from Chrome is low at around 60% so if you are not using the surface as a reflector this is likely to be the correct choice.
The reflection from the deposited surface can be important in some applications. Protected aluminium offers a higher reflection than chrome at approx 85%. The aluminium is still resilient and tough exhibiting good adhesion properties but not quite as good as chrome. So if you are using the reflection you would be better off using aluminium but if not chrome.
Protected silvers offers the highest reflection of the 3 at approximately 95%. There is a downside as out of the 3 it is the most difficult to manufacture. The reason is the adhesion properties of silver make it very difficult to withstand the photolithography process. Silver is nowhere as resilient as chrome or aluminium so wouldn’t be suited to be used in an outside environment as opposed to the other options.
This option is a high contrast black option which was developed in house. The coating is very resilient and offers the highest contrast of the options. This option is particularly good for resolution charts.