Never trust your eye to detect flaws. Run your fingers over all edges of glassware, searching for chips. Your fingers are capable of detecting flaws and chips that your eyes can t. Use a fingernail or a pen to gently tap areas and edges were damage usually occurs. Handles, edges and spouts are easily bumped and should be inspected thoroughly. A dull thud instead of the usual clink tells you that the item is either cracked or has been repaired.
Color is hard to match when repairing an item so inspect articles in the best possible light.
Always carry a magnifying glass when buying. Use it to inspect every inch of an article you are going to purchase. If the dealer objects, he has something to hide. If you are collecting for investment purposes and plan on buying high priced items, a black light is essential. Use it at shows or anywhere that does not extend return privileges.