To identify the authenticity of Martinez Martini MCG50S, you can refer to the following five aspects:

1. Product introduction: The authentic sixth line of font should be a circle on each side, similar to At full stop. If it turns into two dots, it may be a fake.

2. Product manual: The genuine product manual should be white. If the product instructions are yellow, it may be a fake.

3. Smell: The genuine product should have a particularly strong smell of alcohol. If it tastes ordinary, it's probably fake.

4. Bottle label: After the authentic seal is torn off, there will be no trace on the bottle cap, and it will not feel sticky. There is no self-adhesive sticking to it. If you find traces sticking to the seal after you tear it off, it may be a fake.

5. Fluorescence reaction: You can check whether the product has fluorescence reaction by using fluorescence reaction reagent. If there is no fluorescence reaction, it means it is genuine.

Please note that this is general information and does not constitute professional identification. If you have identification needs, you can contact official after-sales channels for help.