Next, look down on the wine and notice the hue of the wine, especially around the edges. Also notice how much color graduates from the center of the glass to the rim. White wines vary from almost colorless, to hints of green or yellow. A brownish tinge is a sign of too much oxidation, caused by contact with the air. Reds tend to tell more in terms of age and quality by their color.
Reds become paler with age.
The rim of the glass is where to look to get a feel for the age of a red wine. The paler and more brown, the more mature. Alternately, a slight brown tinge around the edges of a young red wine may be a sign of oxidation. The following table shows the differences in the color of wine as it ages. The main point in doing this is to aerate the wine, so it releases its aromas.