"RESTORATION" can be accomplished with basically two approaches. The first approach: the stone may be repaired with methods similar to a repair from the era when the original work was produced, using the tools and materials available at that time. This type of restoration is best referred to as "Historic Restoration". Please see our page dedicated to that category of work for more information.
The second category of restoration is an effort to make the object appear as it did originally, using any tools, materials and processes available to us currently. With THIS type of a restoration, one is not trying for an appearance as if it were repaired during the time of original fabrication.... but rather use all available Contemporary tools to make it appear as it did originally.... before it needed any repair or restoration.
The "CORRECT" way to execute any restorative work is to make certain the client/owner is fully aware of the two options, and perform what the owner prefers to reach the desired look!