When picking glassware, keep in mind it needs to withstand heat, hold wax well, and is not likely to crack. A crack while your candle is lit could be disastrous! Some glassware can be too thin. Canning jars are a great option. Not only are they cute, but they also meet the guidelines of withstanding heat and holding wax well. Besides picking an acceptable glass, there are a few best practice precautions you can take to make sure your glass doesn’t crack. http://www.crystalcandlesupplies.com/candle/ceramic-candle/