For centuries artists have found unique ways to produce original artwork, lithographs and prints. Lithography is the process of creating a template for artwork--normally using large flat stone-- to be reproduced in large volume, and has slowly been replaced with the advent of modern printing technology. Prints are simply a reproduction of an original work, normally by use of photographs or Mylar transfer. Distinguishing the difference between an original painting and a print or lithograph can be difficult to the untrained eye, but by learning to recognise a few telltale signs on the piece, you can easily notice the difference.
Look at the painting closely and note if any paint texture is evident. A brushstroke will leave a thickness of paint on the canvas for oil and acrylic works, while a watercolour painting will leave an impression on the paper. Use a magnifying glass to see any evidence of texture. Texture will reveal that the painting is an original work.
Use a magnifying glass to look closely at the painting's surface. Look for any obvious signs of printmaking, such as parallel lines or a dot matrix. If these are visible, then you have a print, made on a inkjet or laser printer. At a distance the colour will seem to flow, but up close you can see the evidence of printing.
Look on the back of the painting and locate any labels that would indicate if the painting is a lithograph, print series or edition. Often these labels are placed on the back of a painting during framing. Some labels are hidden under a brown paper wrap that is fixed to the back of the painting. Peel back the paper carefully, if this is the case, to locate the label.
Look for any copyright symbols or evidence of print series. Many times, if the work is an original print or print series, the artist will have a signature and a number, such as 2/30. This will indicate that the work is the second original print or lithograph in a series of 30.
Note what the work is made of. Many times prints and lithographs are made on hard stock paper, or cardboard, and these are definitely not original paintings.
Contact the artist if a number or website is available for the piece. He or she will be able to tell you exactly what you have, and possibly how much it is worth.