It Is Written

Sterling silver with very little effort becomes very shiny. One could almost use it as a mirror.
Pure silver though pure doesn't have that mirror like shine but it is pure. Well it can shine but takes more work, more effort. And pure silver once shined is hard to tarnish.
Sterling silver is an alloy of silver containing 92.5% by weight of silver and 7.5% by weight of other metals, usually copper but can be also be such metals include germanium, zinc, platinum, silicon, and boron.
Sterling silver with very little effort can be very pleasing to the eye. Sterling silver easily loses its luster in many situations due to the alloys in it. This is because tarnish is more responsive in alloy metals.
Sterling silver is not pure and like us when we don't let God cleanse us like he wants to. We look very shinny but it truth we are just taking the human route to be pleasing to others to see. But inside where God sees, we are not pure. To become pure is a process. To become pure sterling silver must be put into the fire. Heated up to allow what isn't pure silver to float to the top. Then the impurities are skimmed off the top, leaving pure silver. Like this process, we must be put to the fire to cleanse us. Without this we will never be the pure child God wants us to be. This cleaning may not be a pleasant task. It takes alot to reveal the impurities in our life. Being pure before God should be what we want instead of being pleasing before other people.
Once God does manage to get us to that point of being pure silver. Does the work stop? Not by a long shot. While we are still here on this earth we will always be being worked on. Remember to make pure silver shine it takes alot of effort. Once shined though like pure silver we will resist tarnish, we will remain shiny inside and out. If we can hold onto Jesus, that shine will come about. It may not come about here but in heaven you will shine.