What or who, to Pip represents life as a commoner and life as a gentleman?

For Pip, work as a blacksmith's apprentice represents life as a commoner. Estella represents life as a gentleman.

"I further mentioned that as I had been brought up a blacksmith in a country place, and knew very little of the ways of politeness, I would take it as a great kindness in him if he would give me a hint whenever he saw me at a loss or going wrong."

"Then, a burst of gratitude came upon me, that she (Estella) should be destined for me, once the blacksmith’s boy."

"When I got up to my little room and said my prayers, I did not forget Joe’s recommendation, and yet my young mind was in that disturbed and unthankful state, that I thought long after I laid me down, how common Estella would consider Joe, a mere blacksmith: how thick his boots, and how coarse his hands."