Just noticed I pasted the wrong section from the One World Website! Whoops!

Extra baggage allowance for Sapphire frequent flyers*

As a Sapphire frequent flyer, the following special baggage privileges will apply when you fly on oneworld airlines;

• On international or domestic itineraries using the baggage allowance "weight" system - 15 kgs in addition to the ticketed Economy baggage allowance.
  
• On international itineraries, that include domestic sectors, using the baggage allowance “piece” system – one additional bag*, weighing up to 23kgs, up to a maximum of two pieces.
  
• On purely domestic itineraries, using the baggage allowance "piece" system, for tickets with no ticketed baggage entitlement - the assurance of one piece of checked baggage, weighing up to 23 kgs.
  

Customers travelling in First and Business Class cabins will, in most cases, receive an even greater free checked baggage allowance.

*This benefit is not available on British Airways’ 'Hand Baggage Only/Basic' fares.