The casing of this most expensive sandglass is made of hand-blown borosilicate glass. This glass is clean and transparent, shock and heat resistant, safe and durable. The inside of the sand clock is filled with nanospheres. These delicate nanospheres can move like a liquid for 10 minutes at a time. The entire sand watch is not large, 150 mm high and 125 mm wide at its widest point, but it weighs 1.5 kg. This exquisite sand timer craft is limited to 100 pieces in total, and the number is also very small.