Things You'll Need
Instructions
Examine The Frame
Use a magnifying tool to carefully examine all around the frame. Look for a production date on the frame, on the back or in the corner. It may have the name of the manufacturer; if you can identify the manufacturer, you can research when that particular mirror was made. Frames with engraving or embedded sketching, or that are ornately embellished, are more indicative of older age.
Examine the back of the mirror for any identifying information about the production date or manufacturer. Most valuable mirrors date to 1850 or earlier, but a very elaborate design, even from 1900, is still more valuable than less ornate designs.
Carefully remove the mirror from the frame and examine the surface of the glass closely. Typically, antique glass has some ripples and/or bubbles in it, as well as a variety of such colors as greens, blues, and browns depending on chemical traces and how long it has been exposed to UV light. Genuine silver backing will usually feature light spots and clear areas. Older glass may even be a bit wavy. Even newer mirrors' backing may turn black and flake off, so that is not necessarily indicative of an antique mirror. If it's a wall mirror, note the thickness at the top, middle and bottom. Usually older mirrors are noticeably thicker at the bottom. Uniform color, with no significant spotting or chips, increases the value of a mirror.
Closely examine the edges of the mirror. Beveled edges are indicative of older mirrors, since grinding and polishing glass is time-consuming and expensive. Beveled edges indicate the glass is good quality, and the beveled edges add strength to the mirror.
Newer glass is thinner and gives a whiter reflection than old glass, so test its age by holding the edge of a white card right up against the glass. If the card and the reflection appear to be the same white color, then the mirror was most likely made after 1850. Should the reflection appear more of a yellow or gray hue, then the glass was most likely made before 1850.