Here's a suggestion. The noted Australian glass artist Setsuko Ogishi and her husband operate a studio glass business in the Hunter Valley of NSW near the town of Rothbury. The middle range of their product line is called Ogishi Mizuno and is usually signed OM, sometimes also with a date and sometimes also with a sticker. They make paperweights in the OM range.
The example in the Worthpoint advertisement referenced in Reply #1 above is somewhat similar in its internal swirls to the OM paperweight in the first photo below.
A sticking point in this identification is the appearance of flanges on the M (or is it in fact a W?) in both the questioner's sample and the Worthpoint one. The examples I can find of the OM signature for Ogishi Mizuno do not have those flanges. See photos 2 and 3. Unfortunately neither of these signature photos actually comes from the paperweight in photo 1, but I can rectify that with the matching signature in a later post. A sticker is shown in photo 4.
Setsuko Ogishi has an extensive website here
. Some further research is clearly needed. If it seems likely this is an identification, the studio can be emailed for confirmation.