Switch Aquamarine forging adds less Crit Chance than expected

[DarthPoseidon]

Forging aquamarine into my weapons (I tried this with Galaxy Sword and Iridium Needle) adds less critical hit chance than expected: the first level adds +2, and the second and third add +3. Comparing to the wiki, this seems to be about half of what it should be?

Game Version: 1.5.4.2
Language: English
Single-player
Basic farm

I don't know what else would be relevant info but I'm happy to answer questions / post screenshots if wanted.