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How to Make a Refractometer for Kids

A refractometer measures the angle of light as it hits the surface of a reflective surface, for example, that of a gemstone. Make a refractometer that a child can use to differentiate one type of gemstone from another. Supplies from around the home will be supplemented with supplies from an electronics store. Inexpensive gemstones, including artificial ones, can be acquired from a hobby store or a crafts supply house.

Things You'll Need

Newspaper
Index card, 4-by-5-inches
Ruler
Pencil
Paper clip, 2-inches
Gemstone
Refractometer scale
Paper
Refraction index

Instructions

- 1
  Place a sheet of newspaper on a table. Place the index card horizontally on the newspaper. Measure from the lower left bottom edge of the card to the top left edge. Make a dot on the card at the halfway mark. Measure across the card from the dot to the right side. Make an ̶0;X̶1; at the halfway mark on the card.
- 2
  Straighten a paper clip. Push one end of the paper clip through the ̶0;X̶1; and twirl it three times clockwise to enlarge the hole and even the inside edges.
- 3
  Go outside to your backyard. Place the refractometer scale on a table or chair that is not in shade. Place the gemstone on the bubble on top of the scale.
- 4
  Arrange your eye level so that it is even with the gemstone. Hold the index card that is now a refractometer lens about one inch in front of one eye while closing the other.
- 5
  Squint the eye that is looking through the hole as you stare at the scale. Note the position of the black line that is on the scale. Write the corresponding number on the scale on a piece of paper. Look up this number on a refraction index to gain an understanding of the characteristics of the gemstone you are looking at.

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