How to place a Persian rug in time — and why it is hard

Clues that are used

Specialists combine dyes, wool, foundation materials, wear pattern, repairs and design style. Each suggests a range, not a year.

• Dyes: synthetic dyes appear from the late 1800s
• Cotton foundations spread in the 20th century
• Woven dates can be copied or added later

Common traps

Chemical washes and tea-staining can make new rugs look old. Heavy wear may come from use rather than age.

Advice

Treat age claims as opinions unless a written report explains the evidence.