Full Idea
There is a plausible way of distinguishing genuine and mere-Cambridge properties. To decide whether an emerald is green the thing to do is to examine it, but a mere-Cambridge property is settled by observations at a remote time and place.
Clarification
Mere-Cambridge properties are usually whimsical and relational
Gist of Idea
To ascertain genuine properties, examine the object directly
Source
Sydney Shoemaker (Causality and Properties [1980], §06)
Book Reference
Shoemaker,Sydney: 'Identity, Cause and Mind' [OUP 2003], p.220
A Reaction
Scientific essentialism is beautifully simple! Schoemaker is good at connecting the epistemology to the ontology. If you examined a mirror, you might think it contained reflections.