First things first.
Having done that, lets think of how fakes can be identified.
- Fit of the parts
- build quality.
The weight can only be assessed from the real thing. Impossible by photo.
Fit of the parts. Needs a detailed photo of the actual one you are going to get or the real thing in your hand. The photo is not going to be possible in this case.
Shape. This is more difficult. It can be assessed by photo. However, Hero seem to have a fair bit of variability themselves, particularly in the bend of the clip. I got a genuine pack of 10, and had 9 different bend positions. This is actually quite difficult to do without the pen in your hand. As for the jewel in the cap. That one does look a bit pointy, but it can also look like that at some angles, so I'm not sure that it's enough of an indicator on its own.
Build quality. Almost impossible to assess by photo.
So... It's very difficult to do by photo. Don't panic. It just means that from a vendor without a known reputation, you cannot be sure if it's a fake until you get it.
On to the other question of whether the Doctor is the same as a Jumbo. Some sellers use the words interchangeably. 'Doctor' is usually used for the large diameter pen, but it is also wise to look at the photo because the 'Doctor' name is sometimes applied to a Hero pen where the outside of the cap is flush with the barrel and there is a step in the barrel to accommodate this. This 'Doctor' pen is definitely NOT a Hero 616 Jumbo.
Hope this clarifies things a little.