Hi Carla,

Thank you for contacting Mearto with your appraisal inquiry.
Without a signature, label or documentation otherwise attributing this to Dino Martens, the best I can say is this certainly looks like his work and that it can be "attributed to" him without confirming 100% by his hand. Note that signed / labeled pieces nearly always have more value than unsigned pieces.
Based on the photos and information provided, and subject to examination, this is:

A vintage Murano hand-blown black and white glass bowl
Attributed to Dino Martens (1894-1970), Murano, Italy, circa 1950s
Of circular section with lobed rim and black and white pinwheel design, on a circular foot. Apparently unmarked.
3-1/4 inches high, 12 inches diameter
CONDITION: appears to be in good condition
PROVENANCE: acquired at a second hand store
$400-600*
*represents a fair-market value for auction purposes; retail or asking price may vary.

Please let us know if you have additional items to appraise, or questions/concerns, and thank you again for using Mearto.
~ Delia