If it is skillfully applied and historically correct it is often difficult to distinguish from contemporary colour. If you are in doubt you can ask a map dealer. Usually they can distinguish between the two. 3. Pros and Cons. Most dealers and collectors agree that contemporary full colour is best and that bad modern colour is undesirable but after that there is substantial lack of agreement.
Many uncoloured maps are much more attractive with skillfully applied modern colour.
A few collectors prefer maps only as originally issued coloured or not but most dealers agree that skillful modern colour enhances interest and thus value of many maps. It is very much an individual collectors choice. Very few maps have been deliberately faked to deceive but some have been reproduced and occasionally they are confused with the original. There are some obvious signs that they are reproductions. Reproductions are usually larger or smaller than the original.