Beware of altered vintage bags and replicas. It is important to understand that only original vintage is collectible. Replicas (bags “custom-made” from all vintage materials) and altered vintage (vintage bags with recently added decorations or modified parts) are not as valuable, and must be priced much lower than original vintage.
Once in a while, you can see a bag advertised as “custom-made from all vintage materials.” For example, a seller took a vintage metal evening bag by Coblentz and glued on top of its metal body the skin of alligator, snake, or frog, which was previously removed from some old, unrepairable bag. As a result, she got a “Coblentz” bag that looks quite different from the typical Coblentz styles, in order to sell it as “unique,” for much more money. Such replicas can have various skins, furs, feathers and jewelry (pins, watches, rhinestones, beads, etc) glued on their body, frame, handle or any other part. While it's OK to restore designer vintage bags to preserve their original features, it is not OK to intentionally modify their style with the purpose of selling them as “unique,” or “custom-made,” especially for the higher price.
The other group of vintage alterations includes the bags with replaced handles. Because the straps on vintage bags are usually the first to break from age and use, they could be replaced with the new ones. Some of them could have new handles made from matching skin, leather or vinyl, or be replaced with different belts or necklaces. Especially often you can see vintage bags with plastic or metal straps, which are not original to the bag. Note that such replacements usually decrease the value of original vintage, thus must be disclosed in the description.
To check if the skin strap is a replacement, examine its shape. Usually, original softer handles are slightly misshapen due to storage, unless they are structured or semi-structured, with the inside cord (e.g. Lucille de Paris, Rosenfeld, Bellestone, etc.). Then, examine if its color and material match the bag's body. If it's a metal chain, compare the color of the metal and its patina to the frame and the handle mounts. If it's a replacement, the color and the quality of the metal and its finish would be different from the rest of the bag's metal parts. Very few vintage brands used to make handbags with metal straps (e.g. Lucille de Paris and Koret), and if your handbag has such a strap, most likely it is a replacement. The same rule applies to vintage handbags with plastic straps, so often advertised as Bakelite, or Lucite. Most likely, they are replacements, too.
Finally, sometimes you can find an unsigned vintage handbag with a rhinestone pin glued to its body or a frame, to jazz it up and sell for more money, as something “special” and “different.” To confirm its authenticity, examine how the "adornment" is attached to the bag. If it is glued to the bag's body or its clasp, it is definitely a later addition.
Remember that original decorations (rhinestone, enameled or beaded) were usually bezel-, prong-, or pave-set on the frame, or the clasp. The examples include the handbags by Harry Rosenfeld, Koret, and Lucille de Paris. The Martin Van Schaak bag jewelry was attached to the body of the bags by special holders, inserted through the perforated opening on the bag's front panel.
Thus, if you found a vintage handbag with unusual features, such as different skins, leathers, ornaments or jeweled decorations attached to its body or a frame, or if your handbag has an odd looking handle made of plastic chain or metal strap, you need to inspect it very carefully, in order to establish the authenticity of its every part, feature and material. More often than not, such alterations would not be original to the handbag, which make it less valuable as a collectible.