Short answer

A fake Ladybird diamond is a stone set in a replica Blancpain Ladybird watch. In most listings the stone is not a natural diamond. Sellers use cubic zirconia, moissanite, or lab-grown diamond. Replica prices run from about $120 to $900. A real Blancpain Ladybird with a diamond bezel sells in the five-figure range.

Blancpain Ladybird basics

Blancpain launched the Ladybird in 1956. The first models used a small round movement that was the smallest of its time. Current Ladybird watches use mother-of-pearl dials, diamond hour markers or bezels, and cases from about 21.5 mm to 34 mm. Metals include steel, red gold, and white gold. Stone counts and case sizes change by reference number, so check the reference before you compare a replica to a real watch.

Stone types found on replicas

  • Cubic zirconia (CZ): Mohs 8 to 8.5, refractive index 2.17, density about 5.6 to 6.0 g/cm3. No thermal signature. Loses polish with wear.
  • Moissanite: Mohs 9.25, refractive index 2.65 to 2.69. Doubles light, so back facets look doubled under a 10x loupe. Reads as diamond on a basic thermal tester. Fails a multi-tester set to diamond mode.
  • Lab-grown diamond: Mohs 10, refractive index 2.42. Same optical and thermal readings as a mined diamond. Only a gem lab can separate the two.
  • Glass: Mohs 5.5, refractive index about 1.5. A knife tip scratches it. Facet edges look rounded.

Tests you can run

  1. Thermal tester. CZ and glass fail. Moissanite and diamond pass.
  2. Multi-tester with electrical conductivity. Separates moissanite from diamond.
  3. 10x loupe. Doubling of back facets points to moissanite.
  4. 10x loupe. Sharp facet junctions and a frosted girdle point to diamond. Rounded edges point to glass or CZ.
  5. Weight. A CZ of the same size as a diamond is about 1.6 times heavier.

Case and movement on replicas

Most Ladybird replicas use a quartz movement. Some use a low-grade automatic. Gold-tone plating runs 3 to 5 microns on better replicas and under 1 micron on cheap ones. The crystal is mineral glass on most units and sapphire on higher tiers. Count the bezel stones. Replica bezels often carry a different stone count than the reference.

Price ranges, US market

  • CZ bezel, quartz: about $120 to $250
  • Moissanite bezel, quartz or automatic: about $250 to $450
  • Lab-grown diamond bezel: about $450 to $900

These are listing ranges, not fixed prices. They move with metal, case size, and seller. Natural diamond bezels do not appear at these prices.

Labeling and import rules

The FTC Jewelry Guides require a simulant to be named by its material. A CZ stone may not be sold as a "diamond." A lab-grown stone must carry the words "laboratory-grown" or "lab-grown." US Customs and Border Protection bans import of counterfeits and seizes shipments. A watch marked "Blancpain" without authorization is a counterfeit, whatever stones it holds.

Checklist before you buy

  • Get the stone type in writing.
  • Ask for Mohs hardness and refractive index, not "diamond look."
  • Ask if the crystal is sapphire or mineral glass.
  • Ask for plating thickness in microns.
  • Ask for movement maker and caliber.
  • Compare case size and stone count to the reference.