Here are approximate values for different grades:
- Good (G): $5 - $10
- Very Good (VG): $10 - $15
- Fine (F): $15 - $20
- Very Fine (VF): $20 - $25
- Extremely Fine (EF): $25 - $30
- Uncirculated (UNC): $30 - $50 or more
For quarters with a rare mint mark (D for Denver or S for San Francisco), the values can be significantly higher. For example, a 1912-S quarter in Extremely Fine condition could be worth over $100. As always, it's important to have rare coins authenticated and graded by a reputable coin grading service to ensure accuracy and maximize value.