Gur (jaggery) is a natural product of sugarcane. It is in more unrefined form than sugar. It is a brown raw mass of sucrose which gets it color because of other elements found in concentration such as wood ash and bagasse.
Jaggery is commonly made from two products, that are sugar cane and date palm tree.
jaggery contains sucrose, which when absorbed by our body raises blood sugar levels. That means it is as harmful as any other form of sugar.
The only difference is jaggery takes time to get absorbed in the body. People who don't have diabetes can replace sugar with jaggery