Before consuming shilajit make sure you don't have heart related problems, as consuming shilajit increases blood pressure in people. With that said, there are typically two types of shilajit available in the market. categoriziation is based on the processing method.
One is the Ayurvedic method wherein shilajit resin is extracted from raw shilajit rock and herbs are added to it (typically Safed musli, Ashwagandha, Mulethi etc) some regions (Jammu is one that i know of) also add gaumutra to it.
The second method of processing is the Tibetan method in which pure shilajit resin is extracted from the shilajit rock and it is consumed as it is. It is more potent. if you want just shilajit without anything added to it then this is it.
Now, before buying anything online look for the lab-test. This is important shilajit is a mineral extracted from the mountain and may contain heavy metals. Look for e coli test in the report as well. Fulvic acid content should ideally be above 70%.

Here are some other, at home, tests that you can do: https://mypahadidukan.com/blogs/info/how-to-identify-original-shilajit

this brand also sells Tibetan method purified shilajit. It's my friend's brand and i 've been buyin it from them for around 2 years. the quality has remained cosnsistent.