Most of the ghee sold now is made of vegetable oil, similar to margarine. And it's all marked inedible.

My personal opinion is that it is better to light the lamp directly with vegetable oil, such as corn oil, soybean oil and so on.

In ancient times, ghee was extracted directly from milk, so now it is very expensive and hard to buy. I read a senior brother's post detailing how to process butter (real butter, made of milk, not margarine, made of vegetable oil) into ghee. The actual process is very simple.