Gem squash are small and round - about the size of a large grapefruit. The deep green skin sets it apart from other squashes. They have a deep yellow flesh with a lovely sweetish flavour. Gems are low in calories and contain vitamin A and C, as well as iron, folate, potassium and niacin. Gem Squash is often overlooked in favour of its more famous cousins the butternut squash and pumpkin.