String instruments in daily use are subject to wear- no matter how careful musicians are, accidents happen and 300 years are a long time to stay all fresh and in good shape.
Luckily we have a few prime examples of Cremonese violins, violas and cellos which are still in very mint condition and give contemporary luthiers like me the chance to study them- to see what they looked like before a lot of details were worn away.

One good example for a part of an instrument that is prone to be worn due to its prominent placing is the corner.

Eight of them, important features in an instruments outline and each one gets a slightly different ageing treatment due to their position on the body.
The lower corner of the front on the treble side (right side if you look at it) typically gets worn the most being closest to where the bow passes by.
The upper corner on the same side for example may easily be touched by a pizzicato hand. Spruce being softer than maple also makes them more fragile.
Just pay attention next time you have the chance to look at an old instruments. Notice how different the corners are worn.

The best protected corner usually is the upper one on the back treble side (left side when you face the back).

I would like to show you a few examples of a very fresh, a mint condition and a very used Stradivari corner all from his golden period.

The famous Messiah Stradivari, 1716

A Stradivari corner from around 1700 in very mint condition

A fairly worn upper corner of a golden period Stradivari

For me as a contemporary luthier who does make copies of the old masters instruments, it is highly important to get an idea and a feeling for what an old, worn corner had once looked like when it left the makers workshop.
A fresh corner provides much more information on how the woodwork had been executed- the tools used, the size and angle of the chamfer, the original design of the corner etc. -small details which transport the intention of the maker.
To emulate the wear in a natural way you have to think backwards and it needs patience and practice to catch the right look if you try to make a new corner look like it was in use for 300 years.

Here is the upper back corner of my latest violin, before and after I induced some wear.

And this is a picture of a plastercast showing an original Stradivari corner in good condition. Notice how the flow in the outline is still present although other details are worn away.