Would be happy to know which Saudi Coin this is!

Approximate dimensions - Diameter - 17mm | Thickness - 2.5mm-3mm

 It is not a coin - such as it is shown there - 

it is the middle part of this coin 

N#9929 

 Which explains the gouges on both sides, made when it was knocked out. 

I see, is it a minting defect or post-minting damage? What are the possibilities? I am a beginner hobbyist.

It is clearly a post-minting damage, as we can see the spot where force was applied to remove it.

Oh wow.

Maybe somebody wanted to make a piece of jewelry?

I've seen this done with the Mexican 10 pesos - folks pop out the silver centers and use them to make jewelry.

I've seen a pair of earrings and a pendant.