The Legal version :
Complicated or unusual repair – The repair that you have chosen for the Diamond Tree Studio jewellers to undertake is either risky, or has a higher than usual rate of being unsuccessful. While all due care will be taken and the skillsets we have utilised to the full extent of our capabilities, by signing this document you understand that this repair has the possibility of not being successful or is against our recommendations for repair. 
The Diamond Tree Studio is not to be held liable for any damages or disappointments if this occurs. 

The Easy to understand version :
We will do our absolute best but it might not work. You know this isnt something we can be held responsible for.