Steampunkers USA Power Pack Series - Classic Arrow Point 30mm Black Obsidian Gemstone Arrowhead Pendant - Black Necklace 20", Sagittarius Birthstone Stone Type: Obsidian. Stone Color: Black. Pendant Dimensions: 1.25" Long, 0.6" Wide, Approx 0.2" Thick. Pendant Metric: 32mm x 15mm x 5mm. Description: Arrowhead Necklace Pendant Gemstone Symbology: Obsidian # Sincerity, Honesty, Truth, and Grounding. Sagittarius Birthstone (November 22nd # December 21st). Includes Adjustable 20" Black Necklace Cord as Pictured Stones may vary slightly in size, color, pattern, or shape. The item sent to you will be similar to the one pictured first.