Single-sided sturdy and durable acrylic. 

Specification:
Product: DIY Diamond Painting Pendant
Material: High-quality PET + Fancy-shaped Rhinestones + Crystal Rhinestones
Size: 24.5cmX24cm/9.65X9.45in

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