How to identity gear sizes?

[VividVisions]

I bought a bunch of 002 gears, I noticed many of the packages are labeled wrong as far as keyed shaft vs spline shaft. So I would like to measure them to make sure they are the correct ratios. How are the gear sets measured? Diameter, tooth count, pitch? Is there a chart? I appreciate any help. Thanks

[Bruce2]

Are the gears matched pairs?
Count the teeth to figure out the ratio.
Post some pics.

[Clatter]

If the gears were separated from their matched mate you'll have to do some measurements.
They all have the same center-to-center so you'll know you have a pair if that's correct.
That, and if they mesh correctly..