'Genuineness' in the Bible

I am not saying [this] as a command, but proving the genuineness of your love by means of the diligence of others.

The greeting [is] by my hand, Paul's, which is {a sign of genuineness} in every letter: {this is how I write}.

so that the genuineness of your faith, more valuable than gold that is passing away, but is tested by fire, may be found to [result in] praise and glory and honor at the revelation of Jesus Christ,