Would you go for the set square or the protractor look? Well may be the ruler look would suit you best but if you are a Geometry fan then you could opt for all, interchanging them as needed.

The measuring jewelry variety includes Protractor Necklace, Ruler Pierce, Triangle Necklace and Triangle Pierce. Designed by Aquvii, these are available from Mass Item in multiple colors like clear, yellow, pink, green and gray.