Digital Gemology: gem identification and gemstone properties

Everything Digital Gemology measures about one gemstone: refractive index (both rays for doubly refractive stones), birefringence, dispersion, specific gravity, hardness, crystal system, critical angle, what a refractometer, polariscope and dichroscope show, its pleochroic colors and the lines and bands a hand spectroscope shows, with links to the free tools.

{
  "type": "object",
  "properties": {
    "gemstone": {
      "type": "string",
      "enum": [
        "diamond",
        "moissanite",
        "cubic-zirconia",
        "ruby",
        "sapphire",
        "emerald",
        "amethyst"
      ],
      "description": "Gemstone, as its slug."
    }
  },
  "required": [
    "gemstone"
  ],
  "additionalProperties": false
}

Match a stone's test readings against the seven gemstones Digital Gemology covers and rank them, saying which reading fits and which does not. Give any of: refractive index, birefringence, specific gravity, optic character, pleochroism, a spectrum line, or that the refractometer read over the limit. A match is a lead among seven stones only, not an identification.

{
  "type": "object",
  "properties": {
    "refractive_index": {
      "type": "number",
      "description": "A refractometer reading, for example 1.765."
    },
    "birefringence": {
      "type": "number",
      "description": "The difference between the two readings, for example 0.008; 0 for a singly refractive stone."
    },
    "specific_gravity": {
      "type": "number",
      "description": "Specific gravity, for example 4.0."
    },
    "optic_character": {
      "type": "string",
      "enum": [
        "singly",
        "doubly"
      ],
      "description": "From the polariscope: singly refractive (stays dark) or doubly refractive (blinks light and dark)."
    },
    "pleochroism": {
      "type": "string",
      "enum": [
        "none",
        "weak",
        "distinct",
        "strong"
      ],
      "description": "What the dichroscope shows: none, weak, distinct or strong."
    },
    "spectrum_line_nm": {
      "type": "number",
      "description": "A line or band seen in a hand spectroscope, in nanometres, for example 694."
    },
    "over_the_limit": {
      "type": "boolean",
      "description": "True if the refractometer showed no reading because the stone is above about 1.81."
    }
  },
  "additionalProperties": false
}

Two gemstones side by side, and the tests that tell them apart: refractive index, birefringence (doubling of back facets, polariscope), specific gravity, dispersion (fire), hardness, pleochroism and spectrum, each with the free tool that shows it. For questions like 'how do I tell diamond from moissanite?'.

{
  "type": "object",
  "properties": {
    "gemstone_a": {
      "type": "string",
      "enum": [
        "diamond",
        "moissanite",
        "cubic-zirconia",
        "ruby",
        "sapphire",
        "emerald",
        "amethyst"
      ],
      "description": "The first gemstone, as its slug."
    },
    "gemstone_b": {
      "type": "string",
      "enum": [
        "diamond",
        "moissanite",
        "cubic-zirconia",
        "ruby",
        "sapphire",
        "emerald",
        "amethyst"
      ],
      "description": "The second gemstone, as its slug."
    }
  },
  "required": [
    "gemstone_a",
    "gemstone_b"
  ],
  "additionalProperties": false
}

What a hand spectroscope shows for one gemstone: each absorption line and band with its position in nanometres, its cause (for example Cr3+ in ruby) and what it looks like, from Digital Gemology's Spectroscope.

{
  "type": "object",
  "properties": {
    "gemstone": {
      "type": "string",
      "enum": [
        "diamond",
        "moissanite",
        "cubic-zirconia",
        "ruby",
        "sapphire",
        "emerald",
        "amethyst"
      ],
      "description": "Gemstone, as its slug."
    }
  },
  "required": [
    "gemstone"
  ],
  "additionalProperties": false
}