What does 'Crystal 24%' in the material description mean?

Looking first at the number 24, it refers to the weight ratio of lead oxide blended into the raw materials. Generally, when lead oxide makes up 24% or more of the glass raw materials, the refractive index of light increases, resulting in a clear luster and a long, clear resonance when the glass is tapped.

It is substantial in weight. KIMURA GLASS Kimura Glass's Kinugawa 4oz glass has compact dimensions of 5.9cm in diameter and 6.7cm in height, but reaches a weight of 150g^[1]. Even though it is a small size with a holding capacity of only 120ml^[2], adopting the crystal 24% material^[3] allows it to sit stably on surfaces, and its solid weight is fully conveyed when held in the hand.