Are these glasses safe to use?

Most of these vessels can handle wine or water for special occasions, provided you treat them with the care due to fragile antiques. Hand-washing is mandatory after every use to protect the surface. Lead crystal can leach trace amounts of contents if left standing for long periods, so avoid storing liquids in them permanently.

How can I tell the age?

Examine the base for a polished or rough pontil mark, and check the weight and colour of the metal for period characteristics. Tool marks and tiny bubbles in the glass often point to manual production. Compare the stem construction, whether air twist or opaque twist, against established period typologies to narrow down the decade of manufacture.

What is the difference between lead glass and flint glass?

Lead glass incorporates lead oxide into the batch, which increases weight, brilliance, and softness for cutting. Flint glass historically referred to high-clarity glass, though the terms often overlapped in the period. Both materials produce the clear, resonant ring associated with quality drinking vessels from the eighteenth and nineteenth centuries.