The presence of lead in crystal softens the glass and makes it more accessible for cutting and engraving. Lead increases the weight of the glass and causes the glass to diffract light. Lead crystal is made from a mixture of sand, potash (potassium carbonate) and lead oxide. The components are heated to at least 2,400 degrees Celsius until molten and red-orange in color. The temperature is then slowly reduced to the "working" temperature.Glass can contain up to 40% lead, if maximum hardness is desired. On the other hand, crystal can contain less than 24% lead if it has a high proportion of barium oxide, which ensures high quality light diffraction.

The main difference between glass and crystal is the lead content. Glass is composed of sodium and potassium. Crystal is also composed of sodium, but in addition, it contains silicone, and has a lead content of 10-24%. The lead makes the glass heavier and, most importantly, the lead changes the refraction index of the item, which makes it appear brighter and cleaner. Because the refraction index is higher and lead crystal is not as brittle as standard glass, it is possible to make deeper and more complicated cuts in crystal.

To deserve the name "lead crystal" the glass must meet 3 criteria defined by rigorous rates and percentages. Below these measures, one can only talk about "crystal glass" or "crystalline".

Full lead crystal 30%
Metallic oxides PbO > 30%....Density > 3.00....Refractory index > 1.545

Lead crystal 24%
Metallic oxides PbO > 24%....Density > 2.90....Refractory index > 1.545

Crystal glass, crystalline
Metallic oxides ZnO, BaO, PbO, K2O Separately or together > 10%....
Density > 2.45....Refractory index > > 1.520

Crystal glass, crystalline
Metallic oxides BaO, PbO, K2O Separately or together > 10%....Density > 2.40

Lead crystal is a material rich in symbols:
Symbol of life, lead crystal is a reminder of the four elements, ultimate components of life : earth, fire, wind and water.

Symbol of purity, glass has often been used as a representation of innocence and virginity. Many Italian Renaissance paintings show virgins depicted next to glass objects through which light passes without altering them.

Symbol of greatness , lead crystal, considered as a precious material, has often been reserved for the elite. Beyond its symbolic meaning, lead crystal has won acclaim with its sparkle its intensity , its transparency and its unequalled musicality.