• Store Options
  • View Basket
  • Checkout
  • Search
  • Email Us

• Glass Ranges

What is Crystal Glass?

Crystal (high quality glass), according to EU definition, must have an index of refraction of at least 1.520 and a density of at least 2.45kg/l. Lead crystal must contain lead oxide to a level of at least ten percent. Other glass used for stemware can also contain oxides of potassium, zinc or barium.

Lead glass is potassium silicate glass which has been impregnated with lead oxide (from 10% to 28% by weight) in its fabrication. In the case of stemware and decorative glass the goal of the lead is twofold. To increase the refractive index of the glass, and thus its lustre, or sparkle and to soften the glass to enable cutting for decoration
Lead oxide added to the molten glass which gives lead crystal a much higher index of refraction than normal glass, and consequently much greater "sparkle".

Common glass contains about 70% silicon dioxide (silica), which is the same chemical compound found in quartz, and its polycrystalline form, sand.

For non-lead crystal, pure silica has a melting point of about 2000 °C (3600 °F), and while it can be made into glass for special applications, two other substances are always added to common glass to simplify processing. One is soda (sodium carbonate), or potash (potassium carbonate), which lowers the melting point to about 1000 °C (1800 °F). However, the soda makes the glass water-soluble, which is usually undesirable, so lime (calcium oxide) is the third component, added to restore insolubility. The resulting glass contains about 70% silica and is called a soda-lime glass. Soda-lime glasses account for about 90% of manufactured glass worldwide.
Boron may be added to change the thermal and electrical properties, as in Pyrex. Adding barium instead of lead increases the refractive index in a similar way to lead.

Click Here to go back to Glass Advice

Contact Us today or Call 020 7935 4679 to enquire about Riedel Glasses