Reconstruction of the Cosmic Gems arc in the image and source planes with the GravityFM tool (Bergamini et al., in prep.). Top panels, from left to right: Observed F150W image (I); the arc reproduced by inserting radii of the clusters in the source plane spanning the range 0.5 − 1.3 parsec (II, F150W PSF, with noise added); the same, with each assuming radii of 3 parsec (III); and the same, with each assuming radii of 10 parsec (IV). Bottom left panels: Same as in the top panels, but for NIRSpec data (V and VI, see text for more details). Bottom-right panels: Source plane reconstruction and the modeled sources inserted in the forward modeling reproducing the observed arc shown in panel II.