The cost of replacing the back glass on an iPhone 8 varies depending on where you get it done. Apple charges $99 for the repair, but you can also find it done for less at a third-party repair shop. In India, the cost of an iPhone 8 back glass replacement is around 2600 Rs.

If you decide to do the repair yourself, you will need the following tools and parts:

• A heat gun
• A suction cup
• A guitar pick or plastic pry tool
• A new back glass panel
• Adhesive
• A toolkit

The repair process is relatively straightforward, but it can be time-consuming and delicate. Here are the basic steps involved:

1. Heat up the back glass with the heat gun until it is warm to the touch.
2. Apply a suction cup to the center of the back glass.
3. Use the guitar pick or pry tool to create a small gap between the back glass and the frame.
4. Use the heat gun to continue heating the back glass and pry it away from the frame.
5. Remove the old back glass and clean the frame with isopropyl alcohol.
6. Apply the adhesive to the new back glass panel.
7. Carefully align the new back glass panel with the frame and press it into place.
8. Allow the adhesive to cure for at least 24 hours.

Here are some tips for a successful repair:

• Be careful not to overheat the back glass, as this could damage the phone.
• Use a suction cup that is strong enough to hold the back glass in place while you are prying it away from the frame.
• Be patient and take your time, as this is a delicate repair.

If you are not comfortable doing the repair yourself, you can always take your iPhone to a third-party repair shop or Apple.