According to CX own website you get one extra pc luggage as sapphire.
https://www.cathaypacific.com/cx/en_...-benefits.html

However the staff showed me an internal guide that shows that sapphire only get 2 pcs for economy essentials, no extra. How can this be? This was the only reason I booked CX and paid extra for essentials.

Also according to Oneworld it says 1 pcs extra luggage. It does says with small text "exemptions may apply"..
https://www.oneworld.com/travel-benefits

Very disappointing.