Vintage 18ct Gold 0.85ct Emerald Cut Diamond Solitaire Ring Size M 1/2

Vintage solitaire engagement ring constructed from an 18-carat yellow gold band with a platinum setting head. 
The focal point features a single emerald cut clear diamond measuring 6.5 x 5 mm, yielding an estimated face weight of approximately 0.85 to 0.90 carats. 
The gemstone is held in place by a 4-prong white metal box collet setting supported by an open under-gallery. 
The diamond and its top setting box sit at a distinct tilted angle relative to the horizontal plane of the shank shoulders. 
The ring features knife-edge shoulders that taper downward toward a slender, uniform D-shape yellow metal shank. 
4-Prong Setting, Angled Setting Head.
The interior of the band features a stamped hallmark containing the numerical characters 18ct. 
The ring is a UK size M 1/2 and the gross item weight is 2.6 grams.
Item Specifics:

• Type: Ring
• Style: Solitaire
• Occasion: Engagement / Anniversary
• Metal: Yellow Gold
• Metal Purity: 18ct
• Setting Material:
• Main Stone: Diamond
• Main Stone Shape: Emerald Cut
• Main Stone Length: 6.5 mm
• Main Stone Width: 5 mm
• Main Stone Carat Weight: 0.85 ct - 0.90 ct (Estimated from dimensions)
• Number of Gemstones: 1
• Ring Size: M 1/2
• Item Weight: 2.6 g
• Base Metal: Yellow Gold
• Hallmarked: Yes (Stamped 18ct)
• Vintage: Yes
• Original/Reproduction: Original
• Department: Women
• Features: 4-Prong Setting, Knife-Edge Shoulders, Angled Setting Head
• Condition: Pre-owned (setting head is securely attached but sits at a distinct tilted angle relative to the band; light surface wear present)