Hallmark 2000, with the last zero being a small diamond

by deborah a hough
(laconia, nh)

I inherited a lovely five stone princess cut 14k diamond band. On the inside of the band it has 2000, with the three zeros being a small diamond. It also has PLAT and LSC4 inside and 30458. It looked VERY similar to "the Leo" hallmark, but using the date instead. Can you tell me who manufactured this ring and could it be Leo Schachter?