The aril around the seeds of Gac fruit is rich in fatty acids and carotenoids (lycopene and β-carotene). Understanding how these qualities are affected by fruit maturity at harvest may identify indices for quality assessment. Some physical and chemical properties of Gac fruit were determined for fruit harvested between 8 and 16 weeks after pollination (WAP). Fruit respiration rates and ethylene production rates were assessed after harvest and up to 20 days in storage at 20°C. Fruit harvested at 14 WAP had the highest oil (0.27 ± 0.02 g/g DW), lycopene content (0.45 ± 0.09 mg/g FW), and β-carotene content (0.33 ± 0.05 mg/g FW) which declined by 16 WAP. External skin color and aril TSS were indicative of oil and carotenoid contents in aril. Skin color, TSS and potentially firmness were good indices of fruit quality. Harvesting less mature fruit at 12 WAP would be practical as the fruit were firmer and more capable of transport; however, quality during postharvest ripening may be limited. Fruits continued to ripen after they were harvested and an ethylene peak in the least mature fruit may reflect a climacteric behavior but this needs further investigation.