Well, getting more than one will tell you if they re comparable. That alone would indicate a consistent source material. A lapidary might think you had 20 lbs. of nothing and only so many workable karats. A different lapidary might think you had more. So there is room for variance. You can get daily updates on mineral prices on the internet. I keep my specimens, but a sizeable piece of jadeite would be worth more to an artist or jeweler in my mind. You could search jadeite artists nd maybe get a better price. If both your lapidary sources say you would get 200 karats of workable jadeite, you know the price is 10-25 dollars a karat for a piece of jadeite of that quality and color, you will know who was honest. Between the price guide and knowledgeable people you will know more than many walking in. Be patient and thorough.