Gold filled, rolled gold, and gold plated
One area in which vintage pens and pencils are demonstrably superior to their modern successors is in the widespread use of gold filled metal. This is a laminate, in which sheets of solid gold (usually between 12K and 18K) are fused to a base layer, normally of brass. The laminate is typically rolled out afterwards, hence the alternative term of "rolled gold" (one also will see "silver filled" and "rolled silver", though less often due to the lower cost of silver in comparison to gold).
The quantity of gold used can vary, and is sometimes indicated by a fraction: 18K 1/5 would thus indicate a laminate that is 1/5 18K gold by weight. In any case, the gold layer will be much thicker than the microscopically thin deposit laid down by electroplating, and much more resistant to wear, being alloy gold rather than soft 24K (recent improvements in electroplating have enabled much harder deposits, but they remain extremely thin). Often, the gold layer is so thick it can be engraved without exposing the base layer. Needless to say, there is a big difference in appearance between the superficial flash of an electroplated surface and the rich depth of gold filled metal.
Older pens that used electroplated trim were cheap products, and almost all have lost all their plating long ago. Sadly, nearly all modern pens now use electroplating rather than gold filled metal. Many show more trim wear ("brassing") after a few years of use than vintage pens do after several decades.