Pair of Vintage Thai Silver Nielloware Goddess Clip Earrings

A pair of silver Thai fan shaped clip earrings with Mekhala, the Goddess of Lightning depicted with her characteristic crystal and lightning bolts. The goddess is surrounded by a cherry red niello “enamel”. I believe the earrings date from the 1980s. 
 
The clips are marked but I can’t make out the words.
 
A little information about Nielloware:
Nielloware, also called niello enamel silver, refers to that dark background on silver.  Niello isn’t technically an enamel, which is made from a glass compound, but rather a kind of metal alloy typically composed of silver, copper, lead, and sulfur.  However, like enamel, the compound is added to the design as a powder or paste and then fired at a high temperature to melt it into the engraved metal.  Another distinction of most nielloware, is that the niello is added to the negative space around the engraved design, rather than filling in the design itself.  Although the finished product is more of a gunmetal color, the word niello derives from the Latin word for black.  
 
Provenance: The earrings were purchased in Thailand by my father for my mother during a work trip to Thailand.
 
MEASUREMENTS
 
1 ¼” (3.2 cm) wide x 7/8” (2.2 cm) tall. Weighs .27 oz
 
CONDITION

There are no chips to the enamels and the clips are still tight. The silver has a nice patina.