Here are the National Rifle Association's Firearm Grading Standards. There are other systems, but these are the best and most commonly used. You will not go wrong if you learn and use these standards:
NRA Modern Gun Condition Standards
NEW: Not previously sold at retail, in same condition as current factory production.
PERFECT: In New condition in every respect. (Many collectors & dealers use "As New" to describe this condition).
EXCELLENT: New condition, used but little, no noticeable marring of wood or metal, bluing perfect, (except at muzzle or sharp edges).
VERY GOOD: In perfect working condition, no appreciable wear on working surfaces, no corrosion or pitting, only minor surface dents or scratches.
GOOD: In safe working condition, minor wear on working surfaces, no broken parts, no corrosion or pitting that will interfere with proper functioning.
FAIR: In safe working condition but well worn, perhaps requiring replacement of minor parts or adjustments which should be indicated in advertisement, no rust, but may have corrosion pits which do not render article unsafe or inoperable.
NRA Antique Firearm Conditions Standards
FACTORY NEW: All original parts; 100% original finish; in perfect condition in every respect, inside and out.
EXCELLENT: All original parts; over 80% original finish; sharp lettering, numerals and design on metal and wood; unmarred wood; fine bore.
FINE: All original parts; over 30% original finish; sharp lettering, numerals and design on metal and wood; minor marks in wood; good bore.
VERY GOOD: All original parts; none to 30% original finish; original metal surfaces smooth with all edges sharp; clear lettering, numerals and design on metal; wood slightly scratched or bruised; bore disregarded for collectors firearms.
GOOD: Some minor replacement parts; metal smoothly rusted or lightly pitted in places, cleaned or re-blued; principal letters, numerals and design on metal legible; wood refinished, scratched bruised or minor cracks repaired; in good working order.
FAIR: Some major parts replaced; minor replacement parts may be required; metal rusted, may be lightly pitted all over, vigorously cleaned or re-blued; rounded edges of metal and wood; principal lettering, numerals and design on metal partly obliterated; wood scratched, bruised, cracked or repaired where broken; in fair working order or can be easily repaired and placed in working order.
POOR: Major and minor parts replaced; major replacement parts required and extensive restoration needed; metal deeply pitted; principal lettering, numerals and design obliterated, wood badly scratched, bruised, cracked or broken; mechanically inoperative; generally undesirable as a collector's firearm.
Uploaded: 1/2/2020