diff --git a/include/color_helper.h b/include/color_helper.h
new file mode 100644
index 000000000..5982f4946
--- /dev/null
+++ b/include/color_helper.h
@@ -0,0 +1,17 @@
+#pragma once
+#include <string>
+#include <vector>
+
+namespace diskann
+{
+
+class color_helper
+{
+public:
+    void write_color_binfile(const std::string& filepath, const std::vector<uint32_t>& location_to_seller, std::uint32_t num_unique_sellers);
+
+    bool load_color_binfile(const std::string &filepath, std::vector<uint32_t> &location_to_seller, std::uint32_t& num_unique_sellers);
+};
+
+
+}
\ No newline at end of file
diff --git a/src/color_helper.cpp b/src/color_helper.cpp
new file mode 100644
index 000000000..e35066c8e
--- /dev/null
+++ b/src/color_helper.cpp
@@ -0,0 +1,63 @@
+#include "color_helper.h"
+#include "ann_exception.h"
+#include <fstream>
+
+namespace diskann
+{
+
+void color_helper::write_color_binfile(const std::string& filepath, const std::vector<uint32_t>& location_to_seller, std::uint32_t num_unique_sellers)
+{
+    // format: num_points, color_size, unique color count, color content
+    std::ofstream outfile(filepath, std::ios::binary);
+    if (outfile.fail())
+    {
+        throw diskann::ANNException(std::string("Failed to open file ") + filepath, -1);
+    }
+
+    std::uint32_t num_points = static_cast<std::uint32_t>(location_to_seller.size());
+    std::uint32_t color_size = static_cast<std::uint32_t>(sizeof(uint32_t));
+    outfile.write((char*)(&num_points), sizeof(std::uint32_t));
+    outfile.write((char*)(&color_size), sizeof(std::uint32_t));
+    outfile.write((char *)(&num_unique_sellers), sizeof(std::uint32_t));
+    outfile.write((char*)location_to_seller.data(), location_to_seller.size() * color_size);
+    outfile.close();
+}
+
+bool color_helper::load_color_binfile(const std::string& filepath, std::vector<uint32_t>& location_to_seller, std::uint32_t& num_unique_sellers)
+{
+    std::ifstream infile(filepath, std::ios::binary);
+    if (infile.fail())
+    {
+        return false;
+    }
+
+    infile.seekg(0, std::ios::end);
+    size_t file_size = infile.tellg();
+
+    infile.seekg(0, std::ios::beg);
+
+    std::uint32_t num_points_in_file = 0;
+    std::uint32_t color_size = 0;
+    infile.read((char*)(&num_points_in_file), sizeof(std::uint32_t));
+    infile.read((char*)(&color_size), sizeof(std::uint32_t));
+    infile.read((char *)(&num_unique_sellers), sizeof(std::uint32_t));
+    if (color_size != sizeof(uint32_t))
+    {
+        return false;
+    }
+
+    size_t color_data_size = num_points_in_file * color_size;
+    if (file_size != (sizeof(std::uint32_t) * 3 + color_data_size))
+    {
+        return false;
+    }
+
+    location_to_seller.resize(num_points_in_file);
+    infile.read((char *)location_to_seller.data(), color_data_size);
+    
+    infile.close();
+
+    return true;
+}
+
+}
\ No newline at end of file
diff --git a/src/disk_utils.cpp b/src/disk_utils.cpp
index f486b1060..846fb3b89 100644
--- a/src/disk_utils.cpp
+++ b/src/disk_utils.cpp
@@ -1206,7 +1206,8 @@ int build_disk_index(const char *dataFilePath, const char *indexFilePath, const
     std::string mem_univ_label_file = mem_index_path + "_universal_label.txt";
     std::string disk_univ_label_file = disk_index_path + "_universal_label.txt";
     std::string disk_labels_int_map_file = disk_index_path + "_labels_map.txt";
-    std::string disk_seller_file = disk_index_path + "_sellers.txt";
+    std::string old_disk_seller_file = disk_index_path + "_sellers.txt";
+    std::string disk_seller_file = disk_index_path + "_sellers.bin";
     std::string dummy_remap_file = disk_index_path + "_dummy_remap.txt"; // remap will be used if we break-up points of
                                                                          // high label-density to create copies
 
@@ -1392,7 +1393,14 @@ int build_disk_index(const char *dataFilePath, const char *indexFilePath, const
         std::remove(labels_file_to_use.c_str());
     }
     
-    std::string seller_mem_file = std::string(mem_index_path) + "_sellers.txt";
+    std::string old_seller_mem_file = std::string(mem_index_path) + "_sellers.txt";
+    if (file_exists(old_seller_mem_file))
+    {
+        copy_file(old_seller_mem_file, old_disk_seller_file);
+        std::remove(old_seller_mem_file.c_str());
+    }
+
+    std::string seller_mem_file = std::string(mem_index_path) + "_sellers.bin";
     if (file_exists(seller_mem_file))
     {
         copy_file(seller_mem_file, disk_seller_file);
diff --git a/src/index.cpp b/src/index.cpp
index 7a5d7130f..3d6a15c7a 100644
--- a/src/index.cpp
+++ b/src/index.cpp
@@ -15,6 +15,7 @@
 #include "windows_customizations.h"
 #include "tag_uint128.h"
 #include "label_helper.h"
+#include "color_helper.h"
 #if defined(DISKANN_RELEASE_UNUSED_TCMALLOC_MEMORY_AT_CHECKPOINTS) && defined(DISKANN_BUILD)
 #include "gperftools/malloc_extension.h"
 #endif
@@ -290,8 +291,12 @@ void Index<T, TagT, LabelT>::save(const char *filename, bool compact_before_save
     if (!_save_as_one_file)
     {
         if (_diverse_index) {
-            std::string index_seller_file = std::string(filename) + "_sellers.txt";
-            std::filesystem::copy(_seller_file, index_seller_file);
+            std::string index_seller_file = std::string(filename) + "_sellers.bin";
+            color_helper().write_color_binfile(index_seller_file, _location_to_seller, _num_unique_sellers);
+            
+            // will remove after new format loaded
+            std::string old_seller_file = std::string(filename) + "_sellers.txt";
+            std::filesystem::copy(_seller_file, old_seller_file);
         }
 
         if (_filtered_index)
@@ -621,11 +626,35 @@ void Index<T, TagT, LabelT>::load(const char *filename, uint32_t num_threads, ui
         throw diskann::ANNException(stream.str(), -1, __FUNCSIG__, __FILE__, __LINE__);
     }
 
-    std::string index_seller_file = std::string(filename) + "_sellers.txt";
-    if (file_exists(index_seller_file)) 
+    std::string index_seller_file = std::string(filename) + "_sellers.bin";
+    std::string old_index_seller_file = std::string(filename) + "_sellers.txt";
+    if (file_exists(index_seller_file))
+    {
+        //uint64_t nrows_seller_file;
+        //parse_seller_file(index_seller_file, nrows_seller_file);
+        if (!color_helper().load_color_binfile(index_seller_file, _location_to_seller, _num_unique_sellers)
+            || _location_to_seller.size() != data_file_num_pts)
+        {
+            std::stringstream stream;
+            stream << "ERROR: When loading seller file " << index_seller_file << std::endl;
+            diskann::cerr << stream.str() << std::endl;
+            throw diskann::ANNException(stream.str(), -1, __FUNCSIG__, __FILE__, __LINE__);
+        }
+
+        _diverse_index = true;
+    }
+    else if (file_exists(old_index_seller_file))
     {
         uint64_t nrows_seller_file;
-        parse_seller_file(index_seller_file, nrows_seller_file);
+        parse_seller_file(old_index_seller_file, nrows_seller_file);
+        if (nrows_seller_file != data_file_num_pts)
+        {
+            std::stringstream stream;
+            stream << "ERROR: When loading old seller file " << old_index_seller_file << " found " << nrows_seller_file
+                   << " rows, expected " << data_file_num_pts << std::endl;
+            diskann::cerr << stream.str() << std::endl;
+            throw diskann::ANNException(stream.str(), -1, __FUNCSIG__, __FILE__, __LINE__);
+        }
         _diverse_index = true;
     }
 
diff --git a/src/pq_flash_index.cpp b/src/pq_flash_index.cpp
index 48e99342d..990f40bea 100644
--- a/src/pq_flash_index.cpp
+++ b/src/pq_flash_index.cpp
@@ -9,7 +9,9 @@
 #include "label_helper.h"
 #include "pq_flash_index.h"
 #include "cosine_similarity.h"
+#include "color_helper.h"
 #include <limits>
+#include <filesystem>
 
 #ifdef _WINDOWS
 #include "windows_aligned_file_reader.h"
@@ -562,7 +564,7 @@ template <typename T, typename LabelT> int PQFlashIndex<T, LabelT>::load(uint32_
     std::string labels_to_medoids = std::string(index_prefix) + "_labels_to_medoids.txt";
     std::string labels_map_file = std::string(index_prefix) + "_labels_map.txt";
     std::string univ_label_file = std::string(index_prefix) + "_universal_label.txt";
-    std::string seller_file = std::string(index_prefix) + "_sellers.txt";
+    std::string seller_file = std::string(index_prefix) + "_sellers.bin";
 
 #ifdef EXEC_ENV_OLS
     return load_from_separate_paths(files, num_threads, disk_index_file.c_str(), pq_table_bin.c_str(),
@@ -828,8 +830,30 @@ int PQFlashIndex<T, LabelT>::load_from_separate_paths(uint32_t num_threads, cons
 
     if (file_exists(seller_filepath))
     {
-        uint64_t nrows_seller_file;
-        parse_seller_file(seller_filepath, nrows_seller_file);
+        std::filesystem::path seller_path(seller_filepath);
+        std::string extension = seller_path.extension().string();
+        if (extension != ".bin")
+        {
+            uint64_t nrows_seller_file;
+            parse_seller_file(seller_filepath, nrows_seller_file);
+            if (nrows_seller_file != _num_points)
+            {
+                std::stringstream stream;
+                stream << "Error loading seller file. Exiting." << std::endl;
+                throw diskann::ANNException(stream.str(), -1, __FUNCSIG__, __FILE__, __LINE__);
+            }
+        }
+        else
+        {
+            if (!color_helper().load_color_binfile(seller_filepath, _location_to_seller, _num_unique_sellers)
+                || _location_to_seller.size() != _num_points)
+            {
+                std::stringstream stream;
+                stream << "Error loading seller file. Exiting." << std::endl;
+                throw diskann::ANNException(stream.str(), -1, __FUNCSIG__, __FILE__, __LINE__);
+            }
+        }
+        
         _diverse_index = true;
     }