Rayner Refractometer (c. 1947)

Introduced in 1947, this Rayner refractometer—engineered by Bristow Tully—marks an important milestone in the evolution of affordable gem-testing instruments. Created for practical gem identification during the post-war expansion of the gem trade, the instrument combined functional innovation with exceptional accessibility.

Its design features a covered observation shield to block stray light, a dense yellow filter that enhances shadow-edge clarity, and an optional polaroid cap for polarization-based testing. These elements provided improved contrast and more reliable readings without increasing complexity for the user.

Remarkably, the refractometer was offered at a modest £13, making it one of the most economically accessible gemological tools of its time. Its combination of thoughtful engineering and affordability helped broaden the use of refractometry among early gem enthusiasts, jewelers, and students, cementing its place in the history of practical gem testing.

This is a museum archives and no unit is available for sale at this moment.