This script helps decide if an oval shaped diamond has good properties.
You'll have to have the Table %, Depth %, diamond length, and diamond width values on hand (usually found in a GIA report). Other than that you will need to have Python or Go running and working on your computer.
After going to the directory where the script lives, enter one of the following in terminal:
python3 diamond_oval.py
go run diamond_oval.go
Then enter values following the prompts. The script will end with its quality level for each criteria (will be either Excellent, Very Good, Good, Fair, or Poor).
Due to its shape, oval diamonds may have dead light (a bow-tie) in its center area, which can look unpleasant. The severity of the bow-tie is best determined visually. Be sure to view the diamond from different angles!
The Diamond Pro for the criteria reference. The site has some really good pointers.