The aging of wood alters its colour according to the timber from which it is made, and according to the treatment it has received over the years. Even the hidden inside parts change with time; if a drawer-lining is scraped it will show at once how the surface has aged. Equally, the old polished outside surfaces mellow, and repolishing changes the colour of the wood completely. New screws differ markedly from old; prior to about 1850 they did not taper to a point, Also, the slot in the head was hand-cut and seldom central; in modern machine-made screws it is invariably exactly across the middle of the head. Old veneers were cut with a saw by hand, and are consequently quite thick; many of them almost an eighth of an inch. Modern veneers, however, are cut with a machine-driven saw, and are much thinner. This, with other factors, is a useful indication of the genuineness of a piece.
If you are really interested in discovering more ways to appraise antique wood furniture, then the most comprehensive book on all aspects of old English furniture is The Dictionary of English Furniture, by Percy Macquoid and Ralph Edwards. It is in three large volumes, copiously illustrated, and was first issued in 1927. A further edition, revised and enlarged by Ralph Edwards, was published in 1954. Also, an excellent guide to the period 1720-1820 is Georgian Furniture, issued by the Victoria and Albert Museum, 1951. A standard work on French furniture is Les Ebenistes du XVIW Siecle, by Comte Francois de Salverte, of which the fourth edition was published in Paris and Brussels in 1953. Also written in French, but less exhaustive and cheaper in price is Les Meubles Francois du XVIW Siecle, by Pierre Verlet. It is in two volumes: i, Menuiserie, ii, Ebenisterie, published in Paris in 1956. In English the Wallace Collection, London, Catalogue of French Furniture, by F. J. B. Watson, issued in 1956, containing a great deal of information and many illustrations. The more you educate yourself on the matter of fine wood furniture, the better eye you will develop over time, resulting in an antiques collection to make you the envy of all your house guests!