The gems are on one side of the blocks only. The windows are translucent and you can look through them.
From Germany's Bauspiel.
Note that due to popularity, this item is limited to one per customer. Orders with multiples will be canceled.
Measurement: Gemmed Blocks are 10 x 5 x 2.5cm, Storage box is 28.5 x 26.5 x 6 cm
Age Recommendation: 3+ Years