Art Glass Hand Blown Design Iridescent Cobalt Blue Cab Vase Sign'd w/47 on base?

Owned for many years, in excellent original condition, gorgeous, well done beauty. Many shades of Cobalt Blue's, swirls, feathering, pear shaped with a slightly flared rim/top. Done by experienced glass artist, signed but we have never been able to make out the name, initials, etc. D C Sl.... then 47!?

Guess it could have been made in 47, timeless shape, design, color of glass, but not sure. Gorgeous, well done and looking for a new home. Liquidating for a late 2020, early 2021 move to a smaller condo-high rise in central Phx, AZ. Area. From bigger house in outer suburbs! 

Measures: 6 inches tall, 5.5 inches deep, 4.5 inch wide at widest point, 1.5 inch flared rolled rim/top, rolls down under to a 1.75 polished pontil base. With aforementioned info on base.