The "igh" spelling typically represents a long "I" sound in words like "high", "night", "light", "fight", and "bright". However, these words have a long "I" sound because the "igh" combination is pronounced as a diphthong, not a pure long "I" sound.
A diphthong is a combination of two vowel sounds that are blended together. In these words, the "igh" sound is a combination of a long "I" sound and a short "y" sound.
Therefore, while the "igh" spelling does produce a sound similar to a long "I", it is not a true long "I" sound.