Double-sided sturdy and durable acrylic. 

Specification:
Product: DIY Diamond Painting Pendant
Material: High-quality PET + Fancy-shaped Rhinestones + Crystal Rhinestones
Size: 23.8cmX21.8cm/9.37X8.58in

Package Content:
1 x Rhinestone Pendants (Rhinestones need to be glued on)
1 x Chain
1 Set x Rhinestone Bag