A knife made of steel with a hardness of 61 should scratch the glass, and if this does not happen, then it does not meet the declared quality.
This an excellent knife. The knife is as advertised. The quality to price makes this knife a best excellent buy. I recommend this knife. There are no sharp edges on the spine. The knife has a pinch grip. Considering COVID-19 the order came very fast. The seller answered all my questions. Be careful as this knife is very sharp.