Rainbow Moonstone Necklace. Hand-crafted. 57cm long, adjustable size, can be worn shorter. Metal: unknown. Width: 3cm. Explaining a blue-painted back on a moonstone involves clarifying that the technique, known as foil backing or closed-back setting, is a traditional method used to optimize the stone's natural adularescence (the internal floating light). The Concept at a Glance: Optical Illusion: Moonstone relies on internal light scattering. A blue or dark background absorbs excess light and prevents it from washing out the stone. The "Rayleigh Scattering" Effect: The paint acts as a contrast agent. It mimics the deep night sky, causing the stone's natural blue sheen (which results from natural Rayleigh scattering) to pop vividly. Historical Context: Painting or foiling stones was widely practiced during the Art Nouveau and Art Deco periods by master jewelers like René Lalique to enhance a gem's luminous mystery. The Structure: Natural moonstone is made of alternating microscopic layers of orthoclase and albite. The Science: When light hits these microscopic layers, it scatters. Because blue light has a shorter wavelength, it scatters more intensely. This produces the gemstone's famous blue adularescence. The Paint: Transparent or translucent moonstones are somewhat see-through. If light passes entirely through the stone without reflecting back, the blue flash looks weak or "dead". The Contrast: By placing a painted blue or dark backing behind a high-domed cabochon cut, the jeweler prevents light from escaping through the bottom of the gem. Instead, the backing absorbs the excess light and reflects only the brilliant blue flash back to the viewer’s eye. Transparency: High-quality blue moonstones are highly transparent. Jewelers often utilize this backing on these clear specimens to prevent the wearer's skin color from showing through. Settings: If the stone is in a closed-back bezel, the backing is a deliberate design choice. Authenticity: the stone itself is real, but the paint serves as a stylistic "stage" to enhance the gem's natural performance.. * NO SHIPPING TO THE USA* Please note the sizes of the item listed and the description, photos are not the actual size of the item. Photos are enlarged and close ups to show the detail of the item listed. Lighting used to take photos can sometimes alter the colour in the photos and not correspond exactly to the true colour of the item, but we try to minimise differences in colour as much as possible. No extra tests are performed to obtain gemologist certificates, it is very costly and will increase the cost price of the item tremendously. No returns are accepted, see all photos before placing a bid. Also note the delivery costs comprise of postage, packaging, insurance and transport and are non refundable. If you are not satisfied with the delivery costs, then please do not bid on the item. If you do bid, then you agree to these costs and I would greatly appreciate it if you do not leave a negative review based on this. Parcel will be sent by registered mail and tracking number supplied. Once the parcel is sent, I cannot control the delivery time or problems that might arise during this process but if there are any problems, I will do my best to assist in any way possible. Deliveries to some countries may take 3 weeks or longer, please keep this in mind when placing a bid. Thank you.