In many of the antique lamps, smooth round glass jewels were used to represent clusters of grapes and accent points. Ruby red was the color used most often in the old lamps.
When installing jewels, rough the edge with a grindstone so the copper foil will adhere better. Only a very narrow strip of foil is needed. Copper foil is easily trimmed with scissors.
The jewels will show up better if they are positioned slightly above the surface of the form. Place pins under them so the rounded part of the jewel is held above the flat stained glass