In 2025, the Chinese National Museum of Ethnology commissioned newly stitched Dragon Boat Festival toys from state-certified intangible cultural heritage practitioners. The toys sat behind glass reserved for fragile antiquities and remained in storage after the exhibition closed, yet they were never accessioned as state-protected cultural property. Why would the museum not recognise as collectable an object it had commissioned, displayed, and preserved? An official and popular image of China as a continuous civilisation might read this hesitation as the cultural authority of antiquity at work. Drawing on 10 months of embedded fieldwork, we reverse this explanation. Following the toys from acquisition proposal to display case, we show that each stage produced decisions defensible under existing documents, rules, or display conventions. These decisions aligned with a grading habit that recognises value only where age or scarcity can already be claimed, so the toys’ newness and reproducibility predetermined their exclusion. What looks like a cultural disposition is therefore better understood as a set of museum policies and practices that we term the “gravity of antiquity”: the pull towards the old that a museum’s collection and the instruments calibrated to it exert on whatever arrives next, producing an exclusion no single decision intends but all cumulatively uphold.