The Maker

• 1). Look for a maker's mark. These marks are usually found on the bottom of the vase, but may also be located beneath or on a handle, or on what the artist considered the back of the vase.
  
  
• 2). When you've located the maker's mark or symbol, draw it or take a picture if it is large enough so that you can have it near while you research.
  
  
• 3). Research the mark, using a computer or library, and find out if it belongs or belonged to an artist known for their blown glass. If yes, you are on the right track.
  
  

The Look

• 1). With a naked eye or with your magnifying glass, look over the vase and check for bubbles, striations in the color, or uneven areas in the glass. These are signs that it is blown glass.
  
  
• 2). If you have two or more colors in bubbles or striations within the glass, it is very likely that what you have is blown glass. However, if your piece is multiple colors in one solid piece, it is not blown glass.
  
  
• 3). If your vase has a lip, check for a place where the glass appears pinched. This is the result of the glass being cut off of a blower's rod when it is still soft and is an absolute trademark of blown glass.
  
  

The Assembly

• 1). Look at the handle (if your vase has one). If it was clearly made separately and the ends have a pinched look, your vase is very likely blown glass. If the vase is very smooth or if there is no joint at all where the handle is attached, it is not.
  
  
• 2). Check for seams where your vase may have been assembled in parts. Vases that are not rounded are blown in sections and then assembled while the pieces are soft. If you have a vase with angles but no seams, it is not blown glass.
  
  
• 3). Look at the shape of your vase. If it is extravagantly shaped, perfectly geometrical, contains shaped holes, or possesses any other attributes that would have required measuring or touching the piece while it was warm, it is not blown glass.