Vintage Black Amethyst Art Glass Vase 10" Six Point Concave Geometric MCM

Striking vintage black amethyst art glass vase featuring an unusual tall geometric form with six projecting vertical ribs and subtly concave panels.  Under normal lighting, the glass appears nearly black with a deep glossy surface. When held against strong light, it reveals its true rich dark purple / amethyst color. One photo shows the vase illuminated to demonstrate the color.  Rather than a conventional hexagonal shape, the vase has a distinctive softly six-pointed star-shaped profile, with each panel curving inward between the projecting corners. This architectural form continues from the base through the mouth.  The glass is relatively thin and lightweight for its 10 height. The rim has a flat cut/ground appearance, while the bottom is smoothly finished with no visible pontil scar.  No maker’s mark or signature was found. Based on its construction and modernist styling, it appears to be a mid-century piece, likely c. 1950s–1970s. Exact maker and origin are unknown.  Details: • Black amethyst / dark purple art glass • Six-rib concave geometric form • Likely mold-blown glass • Cut/ground-style rim • Maker / origin unknown • Estimated c. 1950s–1970s • Approx. 10 H × 3.125 W • Base approx. 2.875 W • Weight: 12.6 oz  Condition: Good vintage condition with light scratches, scuffs, and minor surface marks from age/use. No major damage apparent. Please review close-up photos of the rim and base carefully.