Striking vintage 14 kt yellow gold pendant set with a large colour-change gemstone, displaying a particularly dramatic range of colours under different lighting conditions. The stone has been examined using several traditional gemological observation methods and shows a combination of optical reactions consistent with a possible synthetic alexandrite / colour-change chrysoberyl-type material, although no laboratory report accompanies the piece and the precise gemstone identity is therefore not guaranteed. The centrepiece is a large rectangular faceted gemstone with truncated corners, mounted prominently within an elaborate yellow-gold pendant. In ordinary photographic lighting the stone displays an attractive violet to purple appearance, with deeper saturated purple visible around the edges and facets. Most notably, the gemstone exhibits a pronounced colour-change effect depending on the light source. Under bright white light, the stone becomes a distinctly dark blue, while under other lighting conditions it shifts toward purple and violet. This strong blue-to-purple change is one of the most visually interesting characteristics of the pendant and is considerably more dramatic in person than can be represented by a single photograph. Several additional optical properties have been personally observed and confirmed: Under a dichroscope, the gemstone displays distinct blue and green components, demonstrating visible pleochroic behaviour. When viewed through a Chelsea filter, the gemstone produces a strong bright red reaction. Under different artificial illumination, a clear purple-to-blue colour change can be observed. Under bright white illumination, the gemstone presents as a particularly deep dark blue. In the lighting used for the photographs, the gemstone appears predominantly violet-purple, with areas of stronger magenta and deep purple produced by the faceting. Taken together, these observations make the stone particularly interesting from a gemological perspective. The combination of blue and green dichroic/pleochroic colours, strong red Chelsea-filter response and pronounced blue-to-purple colour change is compatible with materials encountered in the alexandrite and synthetic colour-change gemstone market. However, these observations alone are not sufficient to establish natural alexandrite conclusively, nor to determine natural versus laboratory-grown origin. The pendant is therefore offered conservatively as containing an unidentified colour-change gemstone / possible synthetic alexandrite, with the observed gemological properties stated transparently for the buyer. The gemstone itself is cut in a large rectangular step-cut form with truncated corners, similar in appearance to an emerald or octagonal cut. Its broad central table provides a large uninterrupted area through which the changing body colour can be observed, while the stepped peripheral facets produce considerably deeper purple and violet reflections. The setting is equally distinctive. The central gemstone is surrounded by a substantial 14 karat yellow gold geometric frame with deeply fluted, radiating decoration. These repeated grooves extend outward from the gemstone in a sunburst-like pattern, creating a strong architectural appearance characteristic of bold Retro and Mid-Century inspired jewellery. A substantial geometric bail continues the angular design of the pendant and allows it to be worn on an appropriately sized gold chain. The contrast between the saturated blue-purple gemstone and rich yellow gold is particularly effective. Gemological observations Main stone: Unidentified colour-change gemstone / possible synthetic alexandrite Observed colour in photographic lighting: Violet / purple Observed colour under bright white light: Dark blue Observed colour change: Purple to blue Dichroscope reaction: Blue and green visible Chelsea filter reaction: Strong bright red Cut: Rectangular step cut / octagonal emerald-style cut Laboratory report: None Natural or synthetic origin: Not conclusively determined Jewellery details Type: Pendant Metal: 14 kt yellow gold Style: Geometric / Retro / Mid-Century inspired Setting: Large central rectangular gemstone in a substantial gold surround Design: Fluted / radiating geometric gold frame Condition: Excellent vintage condition with only minor signs of previous wear The unusual optical behaviour is one of the principal attractions of this piece. Depending upon the illumination, the gemstone can look substantially different, ranging from deep blue through blue-violet to rich purple. Buyers should therefore expect its apparent colour to vary considerably between daylight, bright white lighting, warm artificial lighting and photographic conditions. This is an especially interesting piece for collectors of colour-change gemstones, possible alexandrite jewellery, synthetic alexandrite jewellery, colour-change chrysoberyl, vintage gemstone pendants, 14 kt gold pendants, purple gemstone jewellery, blue gemstone jewellery, pleochroic gemstones, Retro gold jewellery and unusual gemological specimens. Please note that the terms possible alexandrite and possible synthetic alexandrite describe the observed characteristics and are not presented as a laboratory identification. No claim of natural alexandrite origin is made. A recognised gemological laboratory would be required for definitive identification of the gemstone species and its natural or synthetic origin. The photographs form an important part of the description and show the actual pendant offered for sale. Due to the gemstone's strong response to different illumination, photographs taken under one light source cannot fully represent the range of colours visible in person. A substantial and visually unusual 14 kt yellow gold colour-change gemstone pendant, combining bold vintage geometric design with a large stone displaying remarkable blue, violet and purple optical effects.