If I get your question, necklace length for a 1.25" pendant.? Keep perspective, some women have a Sophia Loren "long neck". Some have a Jessica Alba "shorter" neck,...
For a 1.25" pendant the proper "length" for a pendant should just come to top section of the cleavage. Think of a plunging neckline dress, the pendant should "hang" in the happy zone.
Take it from me and a well endowed wife.

Measure one of her current necklaces and apply the math for the pendant.

If the length is right,....well the picture works.,....
