In a large stainless steel saucepan, combine the pears, water, lemon zest and juice. Bring to a boil over medium-high heat. Reduce heat and boil gently, occasionally stirring, for 20 minutes.
Working in batches, transfer mixture to a food processor fitted with a metal blade and puree just until a uniform texture is achieved. Do not liquefy. Measure 8 cups of pear puree.
In a clean large stainless steel saucepan, combine pear puree, sugar, orange juice, vanilla, cinnamon, cardamom, and nutmeg. Stir until sugar dissolves. Bring to a boil over medium-high heat, stirring frequently. Reduce heat and boil gently, stirring frequently, until mixture thickens and holds it shape to a spoon and liquid does not separate.
Meanwhile, prepare canner, jars and lids: Wash and rinse the jars in hot soapy water. Drain the jars well of any excess water. Set the screw bands aside – they don’t require sterilizing. Place the lids – the flat round portion of the two-piece closures – in a small saucepan, cover with water and bring to a simmer. Don’t boil. Keep lids hot until you’re ready to use them.
Ladle hot butter into hot jars, leaving 1/4 inch head-space. Remove air bubbles and adjust head-space, if needed, but adding more butter. Wipe rim. Center the lid on jar and screw band down until resistance is med, then increase to fingertip tight.
Place jars in canner, ensuring they are completely covered with water. Bring to a boil and process for 10 minutes. Remove canner lid. Wait 5 minutes, then remove jars, cool and store.