Concentric Diamondback terrapins for sale. Concentric Diamondback terrapin for sale is available in the following sizes: Diamondback terrapin hatchlings, Well started baby Diamondback terrapins, and Yearlings. We highly recommend the well started baby terrapins for sale over the more fragile Diamondback terrapin hatchlings for sale. All photos are for reference and are not of the animal you will be receiving. We go by age, not size, as each animal grows at its own rate. Hatchlings are 1-3 months, well started are are 3-7 months, and yearlings are 8+ months. Our biologist will send an animal from whatever end of that age range we have available at that time. We do our best to sex the reptiles we sell, however, we cannot guarantee sex for anything that is purchased other than adults. We are accurate on most juveniles and hatchlings, but we do make mistakes as some animals do not show their sex as early as others, depending on many factors. Any species of animal that is capable of being temperature sexed while incubating is sexed in that manner, as there is no way to visually sex them until later in life.