As with all tomatoes, if you give them a gentle squeeze and the flesh yields easily they are ready for harvest. This method works especially well with green-when-ripe tomatoes like Green Zebra (although even with these there is a color change from green to yellowy green).

That said, Sungold starts out green and ripens to orange. If they are orange they are ripe.

Rodney

Sungolds are fully ripe when orange. Test one....if juicy and very sweet - these are like tomato candy - then it is ripe. They will also continue to ripen off the vine. I tend to pick daily.

If they split you waited too long.

^^Yeah, definitely pick the orange ones before a rain.

No splitting and I picked a few and they were good but not as sweet as I was expecting. Somethat are not fully orange are just as soft and fully orange so that did not work. I hav been watching them closely for splitting or a color change. Nothing yet. With new veggies I often use others as a gauge, it is usually obvious when something is ripe but this time I am struggling.

The orange ones are ripe. Just because they aren't as sweet as expected, does not mean they aren't ripe. Growing conditions and treatment can have an impact on the Brix too, but I wouldn't try to guess what's going on in your garden for that.