These are ripe when:
- you see a colour change
- they have a hard skin (can't puncture with fingernail)
- they sound jollow when knocked
- the stem is hard and dry
To harvest, cut off the vine leaving as much stem as possible. Wash them to remove bacteria that might cause them to rot (spray with peroxide if you don't want to use bleach). Store in a cool, dry area out of sun. If they are not quite ripe, but you have to pick them, you can let them cure / ripen in a dry, warm place (80F / 27C).