Guidelines as stated in our terms regarding card engraving:
You must not use signatures or designs for which you do not have the rights.
Designs considered offensive or deemed as advertising will be rejected.
Examples of signatures and designs that will result in rejection include:
Logos, trademarks, and designs referring to companies, sports associations, and similar entities
Designs protected by copyright law
Designs that may obstruct or create confusion regarding security features on the card, such as the PIN code
Political statements, symbols, organizations, or parties
Religious statements, symbols, organizations, or persons
Racist, discriminatory, or harmful expressions and designs
Violence, martial arts, or weapons
Blasphemy
Offensive, provocative, or sexual topics of any kind, including nudity, whether in artistic or pornographic form
Any written text in alphabets other than the Latin alphabet (ABC)
In addition to the above, the line in the engraving itself must not be too thick. This means that your engraving will be rejected if the line is thicker than what corresponds to a line drawn with a pen.