Antique mirrors in mint condition are very rare and hence very valuable. It is possible that if you have an unusual old mirror in not very good condition, you may still get a high price for it. Highly mottled glass will also lower the value, as will severe damage.
Antique mirrors were handmade, so there could be signs of imperfections in the frame. A perfect, mass-produced frame is a sign of a more modern, less valuable mirror. Similar to the glass, the frame should show some signs of wear and tear too - but again, cracks may reduce the value.
New glass is thinner and gives a whiter reflection than old glass. You can test this by holding the edge of a white card against the glass. If the card and the reflection are the same white color, the mirror was made after 1850. If the reflection is more yellow or gray, the glass was made before 1850.
Most experts require that a piece be at least a hundred years old or made before mass manufacturing to be considered a genuine antique. One of the clear tell-signs that a mirror is actually many years old is by a simple examination of the glass.
The first thing you should look for is a maker's mark. There can also be some kind of label, inscription, etc. These details could inform you of when the mirror was made. Other important factors are details such as screws, nails, and hanging fixtures.
Check for signs of ageing
Check the wooden frame carefully for areas of fading or darkening, as well as any stains or woodworm. The mirror glass itself will also have signs of ageing if it is original – look out for any cloudy spots or foxing, as well as any scratches or chips on the surface.
Distressed mirrors are sometimes referred to as antiqued or even vintage mirrors. As a general term, distressed mirrors can have a distressed frame or distressed mirror glass. Many times they have both. Let's have a look at distressed mirror frames and distressed mirror glass.
Antique mirrors were first known by the name 'looking glasses' and they were first produced in Murano and silvered in Venice as early as the 16th Century.
Tip: Place a rod (pen or toothpick) on the mirror. If the point touching the mirror looks like it is directly “touching” its reflection, the glass layer is thin enough and the mirror is probably modern. On the other hand, if the point is separate from its reflection, then it is probably mercury (prior to 1835).
Mirror Silvering: A good mirror should have a thick, high-quality coating of silvering — the silver-nitrate-compound coating on one side of the glass that makes it reflective.
Hint: Plane mirrors always produce virtual, erect images that are of the same size of the object. Convex mirrors always produce a virtual, erect and diminished image. Concave mirrors produce a virtual erect and enlarged image of the object when the object is kept very near (within the focus) of the mirror.
Many antique mirrors were made using heavy materials such as silver or mercury, which contributed to their weight. In addition, the size and thickness of antique mirrors may be larger than those of modern mirrors, further adding to their weight.
Check out the lighting.
Look around and determine whether the lighting seems extraordinarily bright. If so, you might be looking at a two-way mirror. However, if the light in the room is relatively dim, and you can't immediately see through the mirror, it's probably just a standard mirror.
Though called silvering, most modern mirrors use aluminum rather than silver to create mirrors. Aluminum is more reflective than other metals, making it a better choice for making mirrors than silver. The aluminum is applied to the polished glass and bonds with it.
During the Bronze Age (3300-1200 BC), more cultures around the world began crafting mirrors out of bronze, silver, copper, and other metals. One particular group, the Kerma people of Nubia, were particularly skilled at mirror manufacturing. A Bronze Age mirror, Achaemenid/Persian Empire, 550 BC -330BC.
Victorian mirrors
Mirrors of this period often adopted styles of periods past, and were known for being grand or elaborate. Victorian mirrors are usually the most heavily carved, with bold decoration. The Victorians didn't solely favour gilt, but often opted for woods such as mahogany or rosewood.
The first glass mirrors, appearing in the Neolithic period in Turkey, Central America, and other places at least as far back as 6000 BCE, consisted of obsidian, a naturally occurring black glass. When this material was honed carefully into a flat, polished surface, it provided a dark and haunting vision of the self.
Antique glass is typically thicker and heavier than modern glass to accommodate for the process of hand-blown glass production. It is essential to take note of how thick your antique mirror is. If it's a high-quality piece, it will have a thickness that you can easily feel when holding the item.
Whether new or old, many mirrors desilver at some point during their lifetime. Dark edges around the outside of a mirror is a telltale sign that the silver backing is lifting and being worn away. The dark spots will eventually work their way in further. Moisture is usually the primary culprit and cause of desilvering.
A simple reason may be because of an accumulation of dirt and lack of maintenance. Another reason could be desilvering - mirrors are made of glass with a silver backing, and over time the mirror may begin to develop black spots. This is called desilvering and it usually happens due to moisture.
Typically, the thicker the glass, the more expensive (and durable) the mirror. For instance, a 36-inch square mirror with a seamed edge and 1/4-inch thickness usually costs around $80 to $100, while the same mirror with 1/8-inch thickness ranges from $50 to $70.
Gifting a Mirror
Asian cultures believe that gifting a new couple mirror on their wedding day will bring bad luck.
In some cases, your mirror may actually be worth more as it is rather than restored, so it is worth consulting an expert. Antique mirrors can be freshened up so the glass doesn't need to be fully replaced - as doing so can drastically reduce your mirror's value.