Is it forbidden for men to wear gold even a small quantity of it (2-3 grams) a ring for instance?

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

It is forbidden for a man to wear gold whether it is in small or big quantity.‘Ali narrated that the Prophet took silk and held it in his right hand and took gold and held it in his left hand and then he [Prophet] said: “Both of these are prohibited for the males of my nation” [Ahmad, Abu Daawood, and An-Nasaa’i]

Besides, Abu Moosa Al-Ash’ari narrated that the Prophet said: “Gold and silver were made lawful for the females of my nation, and they were made forbidden for the males of my nation.” [Ahmad, An-Nasaa’i, At-Tirmithi, Abu Daawood and Al-Haakim]

What is prohibited by the Prophet is the same as what is prohibited by Allah, as Allah Says (what means):

{And whatever the Messenger has given you — take; and what he has forbidden you — refrain from.} [Quran 59:7] Allah also Says (what means): {Nor does he speak from [his Own] inclination.} [Quran 53:3]

Allah knows best.