There are a few simple tricks to know whether or not an antique will most likely appreciate in value or not over the years.  Besides the fact that an antique adds a sense of uniqueness and character to your home it can also be a beneficial financial investment.  

The first trick is to determine how rare an item is.  Obviously the more common an item is the less its value will be.  A classic example of this is the 19-20th century sewing machine.  Although they are wonderful to look at and aesthetically pleasing, many are kept in an incredible condition and are only worth a few hundred dollars because so many families have a sewing machine stowed away somewhere in their house.  Just because something is old, in a good condition, and an antique doesn't mean it is valuable or will increase in value.

Another idea is to check for desirability.  This is being privy to what is fashionable in the current market.  A good example of this are drapes.  Older drapes were somewhat common, aesthetically pleasing but now they are becoming popular and their price is going up.  The higher something is in demand the higher their price will go up.  Following the trends is another way to figure out whether or not an item will make you some money, but what is difficult is predicting the trends so that you can buy something desirable in advance.  Unfortunately no one knows exactly how to predict the future in this way.

Aesthetics is another aspect of the criteria that will be an aspect of the value of an antique.  The more beautiful or pleasing to the eye an antique is the higher its value will be.  But aesthetics is definitely not everything!  So don't go buying everything that looks beautiful thinking you will make a profit in the long run!  Many beautiful antiques are common and will not increase in value.

The last idea to look out for is authenticity.  Is the product real or fake?  Is there any documentation with the antique that can verify the time period in which it came from?  Does the antique come from an artist with a reliable signature or a company?  These questions can lead to verifying some highly valued antiques.

Hopefully if all of these ideas are taken into consideration you will be well on your way to finding and purchasing a highly sought after antique.  Of course all of this depends on if you can find it...

Below is a picture of a rug that is aesthetically pleasing, rare, desirable and authentic.