Could this be natural diamond?

[JIMMFinsman]

Looks very comparable to. Natural diamond vs quartz. Not flowing in the same direction as a quartz would. 

 

[ynot]

That is quartz not diamond. Check hardness..

[Ludwigia]

Even though Delaware is nicknamed the Diamond State, there are absolutely no diamonds to be found there other than in a jewellery shop.

[Coco]

I agree with all of the above. And I will add that we can see iridescence due to mini-internal fractures that cause the difraction of light, while few things can fracture a diamond that has a hardness 10 on a scale (Moth scale) that goes from 1 to 10. So OK for quartz.

 

Coco

[Mark Kmiecik]

If it's diamond then carborundum paper won't have any effect on it.

[JIMMFinsman]

I'm going to test it as I have some diamond paper as well as diamond drill bit. 

Yes I know there are no diamonds naturally occuring in Delaware. Irregardless I will post the results. It's a nice piece.  

I'm posting another find here shortly. 

[Randyw]

I'm saying quartz too. I used to find pieces like that quite often during my rock collecting days

[ynot]

43 minutes ago, JIMMFinsman said:

diamond paper as well as diamond drill bit.

Diamond will scratch diamond.

You should use sandpaper that is in-between the hardness of diamond (10) and quartz (6.5/7)

Carborundum paper or emery cloth has a hardness of 9, so will scratch quartz but not diamond.

Edited June 8 by ynot

[Mahnmut]

Though I completely agree this is quartz, I have to add that fractures do often occur in diamond. The hardness prevents it from being scratched , its still brittle (and combustible, heat it to 850°C, if it burns it was a diamond.)

best regards,

J