There are many ways to tell whether a perfume is original or not, but the most important thing is that for whichever perfume you are checking, you should know the bottle and the box well rather than focusing only on the smell. So the first thing you should look at is the bottle, and then the box, before the scent itself. Even though every perfume bottle is different, with niche perfumes, when you look inside the actuator, there is often a line across from the nozzle. This is not true for every perfume, so first check online what the original bottle looks like or ask someone who owns the perfume for a photo. The second clue is the font used on the bottle and the box. Check the lettering carefully. My third suggestion is more consistent with niche perfumes: the caps of niche fragrances are generally a bit heavier. Find out the cap weight of the perfume you are checking and weigh it. A difference of 1–2 grams can happen, but ideally it should not be more than 2 grams. My last suggestion is to check the smell of the perfume, but for this you need to know very well how the original fragrance smells. In general, the first three points I explained are more useful for checking authenticity.