In addition an old instrument which appears to be a bargain because of its less than fine condition can cost many times its actual cost because of the expensive restoration it may need. These are instruments where the scroll may be from another instrument. Perhaps the top has been replaced by a new one and made to look very old. This can be very deceiving to the prospective purchaser if that purchaser is not very familiar with the details of a particular maker's style, indeed sometimes the experts can be fooled. The replacement of the top is a much more serious matter which will have a greater effect on the value of the instrument and most likely will have an effect on the tone, sometimes for the better, sometimes for the worst.
Varnish is another important consideration in the purchase of an old instrument.
If an instrument is 150 to 200 years, undoubtedly it has had either partial or full varnish restoration in some form. Some old instruments are overcoated with a very thin clear varnish to preserve what original varnish remains. Some have been preserved with regular French polishing over the years and others have been revarnished. Again we have a very confusing matter, especially in cases where the replaced varnish is very well done so that one might never know. Today there are a fair number of violinmaking schools throughout the world which are highly professional in nature.