Birefringence Delta RI

Audit observed directional RI spread against caller resolution, not an inferred complete principal-index birefringence or mineral diagnostic; unobserved directions may hide larger spread.

Description

Directional refractive-index readings may resolve optical anisotropy.

Directional refractive-index readings may resolve optical anisotropy. Observed spread can be smaller than the full principal-index difference if directions are incomplete.^[1]

Audit observed directional RI spread against caller resolution, not an inferred complete principal-index birefringence or mineral diagnostic; unobserved directions may hide larger spread.

When to use Birefringence Delta RI

Use this tool to audit observed directional RI spread against caller resolution, not an inferred complete principal-index birefringence or mineral diagnostic; unobserved directions may hide larger spread.

Prepare the gemstone measurements, spectra or comparison data and any supplied calibration parameters. Check units, reference conditions and record alignment.

How to use Birefringence Delta RI and understand its results

Prepare the gemstone measurements, spectra or comparison data and any supplied calibration parameters. Check units, reference conditions and record alignment.
Enter observedDirectionalIndices, callerIndexResolution using the field table and calculation rules, then run the tool.
Read observedIndexSpread, spreadMinusResolution, anisotropyResolvedAboveCallerResolution. The explanation below defines the units, signs, ordering and any flags or placeholder values.
If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.

Input field	Meaning	Value type; see rules below	Requirement
observedDirectionalIndices	Observed directional indices	list of number	Required
callerIndexResolution	Caller index resolution	number	Required

Supply a nonempty list of positive directional indices and nonnegative caller index resolution. Return spread, signed spread-minus-resolution and a flag only for strict positive excess.

spread=max observed RI−min observed RI

Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.

Output field	Meaning	Value type
observedIndexSpread	Observed index spread	number
spreadMinusResolution	Spread minus resolution	number
anisotropyResolvedAboveCallerResolution	Anisotropy resolved above caller resolution	boolean

json

{
  "input": {
    "observedDirectionalIndices": [
      1.5,
      1.6,
      1.55
    ],
    "callerIndexResolution": 0.01
  },
  "output": {
    "observedIndexSpread": 0.10000000000000009,
    "spreadMinusResolution": 0.0900000000000001,
    "anisotropyResolvedAboveCallerResolution": true
  }
}

Limitations and assumptions

The tool does not reconstruct unobserved principal indices or identify a mineral.

Numeric inputs and returned numeric values must be finite; an unrepresentable returned value produces an error. Numeric lists are limited to 100,000 entries; the rules above may require smaller limits. Missing required fields, extra fields, wrong value types and violations of the calculation rules are input errors. A successfully returned false flag is an evaluated outcome; its meaning is explained above.

Alternative or Complementary methods

Use Single Reading Refractometer Estimate: Calibrate a single curved-surface spot reading against caller instrument references with propagated reading bounds/extrapolation flag; not a definitive RI, full principal indices or identity lookup. For a complementary task, use Dispersion Fire Value: Interpolate measured optical dispersion at caller two spectral references, retaining anomalous signed dispersion; no fixed mineral fire value or pulse-dispersion alias.

References

Birefringence Delta RI — tool.io

Similar or alternative tools

Single Reading Refractometer Estimate
Calibrate a single curved-surface spot reading against caller instrument references with propagated reading bounds/extrapolation flag; not a definitive RI, full principal indices or identity lookup.
Dispersion Fire Value
Interpolate measured optical dispersion at caller two spectral references, retaining anomalous signed dispersion; no fixed mineral fire value or pulse-dispersion alias.