Hand spectroscope

R. & J. Beck, London
Lacquered brass mono prism hand spectroscope (length 10 cm / 11.5 cm when pulled out). It has an adjustable slit and been used for many years for the identification and verification of gemstones by observation of their absorption spectrum. In its black leather covered hinged case lined with blue velvet and purple silk.
Signed “R and J. BECK. LTD | London”, early 20th century.

private collection