Loose Square-Cut Gemstone in Plastic Setting

The item is a loose, clear, square-cut gemstone, likely a Cubic Zirconia (CZ) or similar diamond simulant, held within a clear, circular, plastic or silicone setting. The stone itself measures approximately 5-7mm per side, exhibiting good clarity and facet definition, indicative of a princess cut. It is secured at its four corners by what appear to be small, silver-tone metal prongs, which are embedded into or attached through the clear circular base. The clear base is flat and thin, with a diameter of about 15-20mm, and serves as a temporary or display mounting rather than a functional piece of jewelry. There are no visible manufacturer's marks or stamps on the stone or its temporary setting. The item appears to be in excellent condition with no visible damage, chips, or scratches on the stone, and the plastic setting is intact. The simplicity of the setting suggests it might be a replacement stone, a component for DIY jewelry, or a sample/display stone. The overall quality of the components suggests a modern manufacturing period, likely within the last 20-30 years.