Add colorized bookmarks based on book element, requires spells to be discovered. It can be turned off in the Client settings. Another tweak setting can make it depend on the Archivist's Eyeglass artefact

src/main/java/electroblob/wizardry/client/WizardryClientEventHandler.java

@@ -1,5 +1,6 @@
 package electroblob.wizardry.client;
 
+import electroblob.wizardry.Wizardry;
 import electroblob.wizardry.client.renderer.overlay.RenderBlinkEffect;
 import electroblob.wizardry.data.DispenserCastingData;
 import electroblob.wizardry.data.SpellEmitterData;
@@ -13,7 +14,6 @@ import electroblob.wizardry.spell.SixthSense;
 import electroblob.wizardry.spell.SlowTime;
 import electroblob.wizardry.spell.Transience;
 import net.minecraft.client.Minecraft;
-import net.minecraft.client.gui.GuiMainMenu;
 import net.minecraft.client.gui.ScaledResolution;
 import net.minecraft.client.gui.inventory.GuiContainer;
 import net.minecraft.client.renderer.BufferBuilder;
@@ -31,6 +31,9 @@ import net.minecraftforge.fml.common.Mod;
 import net.minecraftforge.fml.common.eventhandler.SubscribeEvent;
 import net.minecraftforge.fml.common.gameevent.TickEvent;
 import net.minecraftforge.fml.relauncher.Side;
+import net.minecraft.client.resources.I18n;
+import net.minecraft.util.text.TextFormatting;
+import net.minecraftforge.event.entity.player.ItemTooltipEvent;
 import org.lwjgl.opengl.GL11;
 
 import java.util.ArrayList;
@@ -196,6 +199,15 @@ public final class WizardryClientEventHandler {
 		}
 	}
 
+	@SubscribeEvent
+	public static void onItemTooltip(ItemTooltipEvent event) {
+		if (event.getItemStack().getItem() == WizardryItems.charm_spell_discovery) {
+			if (Wizardry.settings.spellBookColorsRequireArchivistsEyeglass) {
+				event.getToolTip().add(TextFormatting.GRAY + I18n.format("item.ebwizardry:charm_spell_discovery.desc.color"));
+			}
+		}
+	}
+
 	/**
 	 * Renders an overlay across the entire screen.
 	 * @param resolution The screen resolution