A professional diamond appraiser is one of the highest-paid professions. They can determine the authenticity of a diamond and its carat content. They are so familiar with the characteristics of a real diamond that they can properly assess whether a diamond is fake. That is the general rule, something that is original is certainly more valuable than its imitation.
The recipients of the Gospel of Matthew were apparently in the midst of the problem of false teachers with the teachings they spread. This kind of problem really shook God's people who at that time still relied on oral tradition in the forms of their teachings. So Jesus' warning against false prophets is emphasized enough in Matthew. Jesus likened them to wolves disguised as sheep. This depiction implies the trickery of these false prophets which was so sophisticated that it was easy to deceive believers.
Jesus then gave instructions on how to recognize these false teachers. One way is to recognize them based on what they produce. It is from their fruits that a person can be identified. A good tree produces good fruit, while a bad tree produces bad fruit. The Lord Jesus' warning ends with an invitation for every believer to produce good fruit. Thus we are invited to continue to hold on to the teachings of Christ as the true teachings and not be tempted by false teachings that are so persistent in deceiving believers.
Bible friends, in this modern era, forms of deception are still rampant. The proponents package these teachings so beautifully and attractively and use social media as a mouthpiece to spread these teachings. Believers are swayed by various teachings to the point of having difficulty distinguishing between what is right and what is wrong. In the end, the benchmark that we can use is the word of God found in the Bible. Our perseverance in studying it is one way to stay on the right path. Recognize good teaching by its fruit.