Fig. 1. Imitation samples of Nanhong agate and natural Nanhong agate
(a): Sample imitation-1 showing similar hue, luster, and transparency with Nanhong agate; (b): Sample imitation-2 showing similar hue, luster, and transparency with Nanhong agate; (c): Sample imitation-2 showing uneven colour distribution inside; (d): Nanhong agate showing uniform colour distribution

Fig. 2. Micrographs of Nanhong agate Imitations showing typical structures of dyeing (a) and heating (b and c); spot-like hematite (d) in natural Nanhong agate showing
(a): Sample imitation-1 showing granular texture and the dye occurring as luffa pulp-like shape and netlike distribution (arrow); (b): The surface of sample imitation-2 showing nailike structure (arrow); (c): The sample imitation-2 showing a cryptocrystalline texture with abvious colour zonation in the interior by section; (d): Spot-like hematite uniformly dispersing in Nanhong agate

Fig. 3. UV-Vis spectra of two kinds of Nanhong agate imitations and natural Nanhong agate
(a): FZP-1; (b): FZP-2; (c): TR

Fig. 4. Infrared absorption spectra of two kinds of Nanhong agate imitations and natural Nanhong agate
(a): Infrared spectra of sample imitation-1; (b): Infrared spectra of sample imitation-2; (c): Infrared spectra of Nanhong agate

Fig. 5. Infrared absorption spectra of organic matters in FZP-1 W: Water; OM: Organic matters

Fig. 6. Raman spectra of two kinds of Nanhong agate imitations and natural Nanhong agate Q: Quartz; OM: Organic matters; M: Moganit; Hem: Hematite
(a): Raman spectra of sample imitation-1; (b): Raman spectra of sample imitation-2; (c): Raman spectra of Nanhong agate