Luxury means different things to different people & luxury assets can certainly hold some of their value or even increase. However there is a trend today to modify that luxury item to make it truly unique & personal to the owner which may lead to an increase in status. Is this trend adding to the exclusivity of your luxury asset or harming your asset? Some of the modifying we are currently see include high end watches like Rolex & Breitling having diamonds added or special engravings. These modification are certainly not cheap but is it going to lead to an increase value? Unfortunately this is not always the case. Certain brands are known for their exclusivity & craftsmanship & adding your own personal twist is often not what future buyers are looking forward.
If your aim is just to add your personal signature that is great but if it is to increase your luxury assets value it may not have the result you are looking for.