When you try to determine the clarity of your wine, you’re really looking for two things—how clear the wine is and if there is any sediment. 

First, and this may seem obvious, your wine should be clear.  Depending on the depth of the color of your wine, this may be difficult to determine, but make sure that you are judging the wine on whether it is dull or murky looking and not on the depth of the color.  A clear wine can be deep colored.  However, if a wine is cloudy, you know it’s likely flawed. 

If you’re having trouble determining the clarity of your wine, remember to tilt your glass.  As you do that, look through the liquid that is closer to the rim, rather than looking through the center of the glass.  You should be able to determine clarity with the wine glass in this position. 

Second, you should check your wine for sediment, not because the sediment is a bad thing (it’s not), but because it gives you some information about the wine.  The most common forms of sediment are caused by aging (mostly in red wines), by lack of filtration, or by tartrates (mostly in white wines).  As wines age, there is a breakdown of pigment and tannins that collect at the bottom of the bottle.  This sediment, which is like the sediment you will find in an unfiltered wine, can be bitter tasting, but is completely harmless.  If you have crystals that look like shards of glass in your white wine, or like red sugar crystals in your red wine, don’t panic!  These are tartrate crystals and indicate that the wine was exposed to cold temperatures after it was bottled.  These crystals are also harmless.  As a slight aside to help with your next game of Trivia Pursuit, these tartrate crystals also form on the inside of barrels during the wine making process.  When this happens, they’re scraped off and turned into cream of tartar.